Be a half full rather than a half empty type of person. what time of literary device would this be? and why?

"it's more of an essay than story, but perhaps it is best described as a mood-piece: it uses a lot of musical imagery, not to mention sea imagery, religious imagery, and any other imagery that suits his purpose."

answer is b,

"the tracer looks harmless in flight, but the pilot’s bitten lips and white knuckles suggest how dangerous it can be."

it was correct.