The answer to your question would be option A: <em>It builds suspense as we realize that Rainsford hears gunshots but cannot see anything</em>.
Explanation:
This passage builds up the suspense in the story because our hero is having difficulties of how to cope with the challenges ahead of him. To start with, we are told that Rainsford strained his eyes to see but couldn't see anything as he felt he was seeing things through a blanket. This shows that he didn't have a clear view and build suspense as this puts our hero in a vulnerable position.
