The answer is A: Use dialogue to make the writing come alive. B. Expand a description by telling more about what happend.
Adding a dialogue is one way to explode a moment; also by expanding a description because these will help emphasize the moment with every moment and sensation being expressed. Using details of everyting the writer is seeing, hearing and thinking at the moment. It's like a movie playing in slow motion. A dialogue is perfectly fit for this function.