The correct answer is A. on.
The preposition “on” is used to indicate a specific day or date. In this case, the speaker is asking to be invited to the friend’s birthday celebration, which is a specific event that will take place on a particular day.
The other options are not as appropriate in this context. The preposition “over” is used to indicate a period of time, not a specific day or date. The preposition “in” is used to indicate a location, not a time. The preposition “for” is used to indicate a purpose, not a time.
Here are some examples of how the preposition “on” is used in other contexts:
- I’m going to the store on Saturday.
- My birthday is on February 25th.
- The meeting is on Tuesday at 10am.
- The concert is on Friday night.