DISTANT
The word "distant" is an adjective that describes something that is far away in space or time. In this case, we are looking for the word that is most similar in meaning to "distant" among the given options.

Options:

a) Far
The word "far" is an adverb that means at, to, or by a great distance. It can be used to describe something that is at a distance or a long way away.

b) Removed
The word "removed" is an adjective that means taken or moved away from a particular place or position. It can also mean not closely related or involved with something.

c) Reserved
The word "reserved" is an adjective that means not openly expressing feelings or opinions. It can also mean kept for a particular person or purpose and not available for others to use.

d) Separate
The word "separate" is a verb or adjective that means to move or be moved apart or into different places or directions. It can also mean not joined or connected with something else.

Explanation:

Among the given options, the word "reserved" is the most similar in meaning to "distant". While "far" and "separate" can also describe something that is far away, "reserved" is the best choice because it suggests a sense of distance in terms of not openly expressing feelings or opinions. When someone is reserved, they tend to keep their distance and not reveal much about themselves. This aligns with the idea of being distant.

Conclusion:

In conclusion, the word "reserved" is the best choice among the given options as it is the most similar in meaning to "distant". It conveys the idea of keeping a distance, both physically and emotionally.