The sympathetic nervous system responds to threats (for example, an angry lion walks near you) through the fight or flight mechanism. In the prior example, you could choose to battle the lion (fight) or run away from the lion (flight).

The hindbrain is composed of structrures responsible for the control of heart rate, respiration and blood pressure. 

A subdivision of the Autonomic Nervous System, the Parasympathetic Nervous System is responsible for returning the body to a calm state after experiencing stress or arousal. The Sympathetic Nervous System arouses the body (i.e. - pupil dilation, increased heartbeat, sweating, etc.). The Somatic Nervous System is responsible for voluntary muscle control.

The Central Nervous System (CNS) and Peripheral Nervous System (PNS) are the two major divisions of the body's nervous system. The CNS is comprised of the brain and spinal cord, while the PNS is all the nerves outside of that. Further subdivisions of the PNS are the Somatic Nervous System (for voluntary muscle movements) and the Autonomic Nervous System (for responses to stress). The Autonomic is divided between the Sympathetic Nervous System (arouses the body under stress) and the Parasympathetic Nervous System (calms the body down after stress).

The Occipital Lobe is responsible for processing vision. The Frontal Lobe controls emotions in its prefrontal cortex.

When the cerebellum is depressed (such as from alcohol use), the ability most typically impaired would be the one to walk in a straight line because the cerebellum controls and coordinates muscle skills. 

The ability to think abstractly is controlled by the frontal lobe, the ability to process visual information is controlled by the occipital lobe, ability to incoporate new memories into a web of old knowledge is controlled by the hippocampus, and the ability to feel emotion is controlled by the amygdala. 

CAT or CT scans use the densities of tissues in order to produce a 3D image of the brain's structures (but not waves or activity), which can then be used to find tumors. 

EEGs detect electrical activity in the brain and are often used in sleep research. fMRIs detect brain activity by showing blood flow in the brain. PET scans detect brain activity by showing how much of a certain substance is being used in a certain part of the brain. Ultrasounds are not generally used for the brain and are most commonly used for fetal imaging. 

The hindbrain is the most basic and essential part of the brain because it controls the simplest biological functions that sustain our lives, such as respiration and heartbeat. The hindbrain is made up of structures such as the medulla and the cerebellum. The other two major areas of the brain are the midbrain, which controls simple movements in conjunction with sensory input, and the forebrain, which controls complicated emotional and cognitive functions. 

The limbic system is commonly thought of as the hippocampus (memory), amygdala (emotion), thalamus (sensory information), and hypothalamus (basic drives, homeostasis).

Each other answer choice had one wrong structure in the list. The temporal lobe controls hearing and language, the cerebellum controls basic motor skills, the tectum controls orientation in a new environment, and the medulla helps control heart beat and respiration. 

The cerebellum resembles the much larger cerebrum. It makes up  of the brain's volume and has two hemispheres. The cerebelum's primary function is to regulate muscle control and activity.