The related words must be seen as sharing the general notion of “being certain and determined.” This shared meaning becomes very obvious when you realize that tentative is different from the others, even if they themselves differ in degrees. The word “tentative” means “not certain or temporary.” Sometimes, when we are asked a question, we must provide a “provisional answer,” meaning an answer that is temporary—a first hunch, though requiring follow-up thought and research. All of the other words indicate some kind of certainty. A resolution is a decision to do something, usually made with firm conviction. A “resolute attitude” is one that is so resolved to do a given resolution. An “unwavering devotion” to something is a devotion that does not stray (waver) from the metaphorical “path” of that devotion. If you are inflexible, you will not change from your choices. Perhaps this is a bad attitude, but for this question, it merely matters that we see the fact that it is quite different from “tentative.”

Each of the similar words here pertain to color or vision. The only word in this group that might cause confusion is “tone,” which could be interpreted in the auditory sense (“the tone of an instrument or a voice”) or as the general description of character (“the tone of the article; the tone of the discussion”). Still, there is a visual sense in which tone indicates the brightness of the color. While this world could be the one that does not match the others, the word “pungent” is completely outside the group of “visual” words, as it means a strong odor or taste. (Likely you have heard the expression, “A pungent aroma”).

Each of the words in the set of related terms indicates something pertaining to the anatomy or the functioning of the human eye. This should be obvious in the cases of “retina,” “pupil,” and “lens.” The likely difficulty for this problem is making a distinction between “optical” and “visionary.” The word “optical” most often is used to describe something that is related to sight. An “optical illusion” is a trick of sight (caused by the bending of light rays). Similarly, an "optometrist" is an "eye doctor” focusing on the correcting of vision. While the word “visionary” likely seems equivalent to “visual,” it really indicates something or someone who can metaphorically see things in the future with great imagination and often in a way that notices trends before they happen. This is not directly connected with physical vision or the physical eye as are the other words.

The four related words all indicate the state of being aware of something, though none of them indicate anything more than the awareness itself (or at least do not indicate deep awareness). The word “comprehensive” means complete and thorough, and thus does not allign with the meaning of the four related words.

"Deny" is a verb which means to refuse to give or grant something as well as refusal to admit the truth or the existence of something. You might deny the existence of aliens; or you could deny your responsibility for breaking the TV. All of the other words, "beautiful," "slow," "playful," and "competitive," are adjectives that describe something. "Deny" does not fit with these words because it is not the same part of speech.

First, observe that all of these words pertain to being different in some manner. Still, there is a distinction between being “opposite” and being merely “different.” Two things can differ by a mere degree—as bright green differs from a hue of green that is slightly less bright. Two such things would definitely not be opposite each other (at least in any meaningful manner of speaking). The other related words all express the same sense of opposition.  Two “antithetical” things are completely opposed. You might say something like, “Paul was the utter antithesis of Sally. While she was extremely disciplined and rigid, he was lax and quite slovenly.” Two “contrary” things are opposed. To say, “On the contrary” is synonymous with saying, “In opposition to the previous point.” Finally, two “inversed” things are opposed.