The lymphatic system functions to return extra fluid that has leaked from the capillaries into interstitial space. It takes this fluid and returns in back into the blood circulation through the right atrium. Fluids from the lymphatic vessels pass through lymph nodes to be screened for pathogens before collection in the right atrium. The lymph does not return to the circulatory system through any other circulatory vessels.

There is an inverse relationship between the cross sectional area of a blood vessel, and the velocity that blood travels through it. The below equation shows the relationship between flow rate, area, and velocity.

Flow rate is constant throughout a system: .

For this equation, it is important to compare the combined cross-section area of the vessel type, rather than a single vessel. Capillaries are extremely small, but have a very large combined area compared to other vessels. In order to keep the flow constant, a large area correlates with a slow velocity. Intuitively, since nutrient exchange occurs in the capillaries, it makes sense the blood would flow most slowly through these regions.

Areteries need to be thick and able to withstand strong, sudden increases in pressure because they recieve blood more directly from the heart. The aorta in particular is very thick and able to expand with a large increase in blood volume. "Compliance" is the word that decsribes a vessel's ability to do this. Veins are thin and collapsable, and contain one-way valves to prevent blood from flowing backwards as it moves against gravity towards the heart.

Arteries always carry blood away from the heart. Most carry oxygenated blood, but the pulmonary artery carries deoxygenated blood from the right ventricle to the lungs so that it can reoxygenated and sent back to the heart.

The aorta is where the blood pressure is greatest, in order to pump blood to the entire body. Capillaries have relatively low blood pressure, but have greater pressure than veins due to their small diameter. Veins carry blood that has traveled a greater distance from the heart; the flow is slower and the pressure is lower. In order to bring the blood back to the heart, the veins must contain valves which prevent the back flow of blood. Arteries, on the other hand, do not need valves because of their great pressure that keeps continuous flow in one direction.

It is important to remember that these nutrients go through the liver before entering the general circulation. Amino acids and carbohydrates are absorbed through the intestine's epithelial cells into the hepatic portal circulation, then to the liver, through the inferior vena cava, and finally into the heart. From the heart, these nutrients are pumped from the left ventricle to the rest of the body's tissues.

Of the available answer choices, we would expect blood pressure to be the highest in the arterioles because they are closest to the aorta and major arteries, from where blood is directly pumped. Of the choices blood pressure is greatest in the arterioles and lowest in the veins.

Note that overall blood pressure is highest in the aorta, however the question specifies that we are only looking a a select portion of answers.

Veins and venules hold approximately 65% of blood in the body at rest. Because of their large luminal diameters, veins are capable to storing much of blood in the human body.

Arteries carry blood away from the heart and have thick, elastic layers that allow for build up of high pressures due to high volume flow. Capillaries are the smallest vessels in the body, and act to facilitate exchange of gas, nutrients, and waste products between blood and tissues. 

Once blood enters the left ventricle, the left ventricle contracts and pushes blood out of the heart into the aorta. The contraction of the left ventricle pumps blood into the aorta at a fast velocity. Blood velocity becomes slower as it reaches the capillaries and then speeds up again in the veins. Veins must use valves to pump blood against gravity, and therefore does not move blood as quickly as the aorta. The aorta is the best answer.

The circulatory system follows both the systemic and pulmonary circuits. Deoxygenated blood is returned from the systemic circuit through the vena cavae into the right atrium. It then goes into the right ventricle after passing through the tricuspid valve. From the right ventricle it enters the pulmonary circuit through the pulmonary artery, which carries deoxygenated blood from the right ventricle to the lungs, where it gets oxygenated. From the lungs it goes through the pulmonary veins into the left atrium. From the left atrium it goes into the left ventricle through the mitral valve, and is returned to the systemic circuit through the aorta.

Deoxygenated blood would be found in mostly in systemic veins, including the vena cavae, pulmonary arteries, and the right side of the heart. Oxygenated blood would be found in systemic arteries, such as the femoral artery, pulmonary veins, and the left side of the heart.