Fill in the blank with the most appropriate word.
She ________ to the market just now.

In the given sentence "She went to the market just now," the most appropriate word to fill in the blank is "went."

The verb "went" is in the simple past tense, and it is used to describe an action that happened in the past at a specific point in time. The sentence indicates that she completed the action of going to the market just a short while ago.

The other options do not use the correct verb form for the given sentence. Option A, "goes," is in the simple present tense and does not match the past timeframe mentioned in the sentence. Option C, "is going," is in the present continuous tense, which does not convey a completed action in the past. Option D, "going," is a gerund form and is not a suitable verb form for this sentence.

Therefore, the correct answer is "B. went."