The correct answer is C. since.
The word “since” is used to indicate a point in time in the past from which something continues to happen or be the case. In this sentence, the speaker is saying that they have not had a call from him since last Wednesday. This means that they have not had a call from him at any time after last Wednesday.
The other options are not correct because they do not indicate a point in time in the past from which something continues to happen or be the case. The word “for” is used to indicate a period of time during which something happens or is the case. The word “in” is used to indicate a location or position. The word “on” is used to indicate a specific day or date.
Here are some examples of how the other options could be used in a sentence:
- I have been working for this company for 5 years.
- I live in a house in the suburbs.
- My birthday is on February 25th.