Question

Which statement will most effectively communicate your refusal?

Answer 1

Answer:

A: I don't want to do that so no

By asking if anyone will find out, you are basically saying yes. When saying I really shouldn't do it, you are not giving a concrete refusal. It also sounds like you maybe want to. When saying your brother wouldn't want to, you are not saying no, just stating something someone else said. A would be most effective since it is a clear and concrete refusal.