The correct answer is A. at.
The preposition “at” is used to indicate a specific location or position. In this case, the speaker is saying that the person came to a specific location, which is the market.
The other options are not as accurate. The preposition “into” is used to indicate movement into a place. In this case, the speaker is not saying that the person moved into the market. The preposition “across” is used to indicate movement from one side of something to the other. In this case, the speaker is not saying that the person moved across the market. The preposition “of” is used to indicate possession or association. In this case, the speaker is not saying that the person is associated with the market.
Here are some examples of how the preposition “at” can be used:
- I met him at the market.
- The store is located at 123 Main Street.
- The party is at 8:00 p.m.
- The meeting is at 2:00 p.m.