He doesn't want other people in the car with you, we would be worried what happened.
The answer would be C because you really don't need to know that.
I had to look for the options and here is my answer:
This is a question based on Shirley Jackson's short story "The Lottery". One instance in the story is that, the boys built a big pile of stones. How this help create suspense is that it keeps the readers wonder why the boys built such thing.