“Tenacious” means stubborn, not going to let anything stop you, or "determined." As for the other answer choices, “excessive” means in an amount that is more than is necessary or wanted; “congested” means backed up or clogged; “serene” means peaceful and quiet; and “frenetic” means fast-paced and stressed.

“Fervent” means intensely passionate about some particular cause or ideal, so "intense" is the correct answer. As for the other answer choices, “sagacious” means wise; “wanton” means random; “vicious” means cruel and desiring to cause pain; and “simultaneous” means happening at the same time as something else.

“Judicious” means careful and "prudent" when referring to people and reasonably considered when referring to decisions. As for the other answer choices, “robust” means strong and hard to break; “flagrant” means obviously and openly outrageous; “akin” means similar to; and “astute” means clever and observant.

"Amicable” means friendly and good-natured, so "friendly" is the best answer choice. As for the other answer choices, “selfish” means thinking of only oneself instead of others; “selfless” means generous, caring about others more than yourself; “aimless” means without purpose or pointless; and “fortified” means strengthened, reinforced, or protected.

Someone who is “obsequious” is groveling and pays compliments to someone who has power in order to gain that person's favor. This means that "servile," which means excessively subservient and fawning, is the best answer choice. As for the other answer choices, “domineering” means in charge or in control; “abrupt” means happening quickly, suddenly, and without warning; “obnoxious” means rude, loud, and ignorant; and “bereaved” means in mourning for the loss of a loved one.

“Spineless” means lacking gumption, confidence, and autonomy, so "craven," which means weak and afraid, is the correct answer. To provide further help, “whimsical” means silly and quirky; “quarrelsome” means argumentative; “burdensome” means worrisome or arduous; and “loathsome” means deserving of hatred. 

The word "reflective" can be used to indicate a surface on which something reflects an image. The idea is that something is "bent back"—i.e. the light rays are bent back from the surface and sent to the viewer. A person is reflective when he or she is bent back on himself or herself. That is, such a person thinks deeply and ponders. Now, such a person will likely be quiet and may also be very intelligent. However, these meanings are secondary. The best synonym for reflective is the one that catches the ponering and thoughtfulness of a reflective person. Thus, the answer is "thoughtful".

The word "passive" actually comes from Latin roots that mean, to suffer or have something happen to oneself. Thus, when you throw a rock at the wall, the wall is "passive" in that it "suffers" to have the rock hit it. It receives the rock's action. Passive people let things happen to them. We call someone a "passive learner" when he or she merely accepts what a teacher says and does not think it through for himself or herself. However, a passive person is not necessarily sluggish or lazy. Thus, these two options are not correct. The best option provided is "submissive." The word passive can be used to describe the submissive attitude described above, especially in the case of the passive learner. Such a person submits to the teaching of another person.

When someone is frugal, he or she is very careful with his or her money. Thus, we might say of a person, "Ronald was well known for his frugal temperament. He rarely spent any money, and when he did, it was spent very wisely." The best option among those provided is "thrifty." To be "thrifty" means to be careful with one's money and other possessions.

The word "candid" is actually rather neat. It comes from Latin roots meaning white. Certain political candidates in the ancient world wore white robes—hence, they were candid-ates. We use the word "candid" to mean honest or truthful. This is because such a person does not "color over" the truth! Thus, such a person is honest and pure, at least in speech!