Answer: B) But it's not pretty sight.
Step-by-step explanation: An euphemism is a polite, agreeable or inoffensive word or expression that is used to refer to things which people may find upsetting or embarrassing to talk about. In the given excerpt from "The Gun" we can see an example of an euphemism when the Captain said that what he saw through the eyepiece or the telescope was "not pretty sight" because what he saw was actually horrible, but he uses the expression "But it's not pretty sight" to cause a softer impact.