I looked . . . . . . . . you at the party, but I didn’t see you. A. to B. at C. for D. on

The correct answer is: C. for

The preposition “for” is used to indicate a search or an attempt to find something. In this case, the speaker is looking for the listener at the party.

The other prepositions do not make sense in this context. The preposition “to” is used to indicate a destination or a goal. The preposition “at” is used to indicate a location or a position. The preposition “on” is used to indicate a surface or a support.

Here are some examples of how the preposition “for” can be used:

• I looked for my keys everywhere, but I couldn’t find them.
• I’m looking for a new job.
• I’m waiting for my friend.
• I’m looking forward to the holidays.