I'm pretty sure it is C. The reasons being that the poem is called "We Wear the Mask". That means that they are showing one thing on the outside, but are saying something different on the inside. Like they are pretending. C makes the most sense because the passage states that they smile on the outside but their souls are crying.
If anything, it made it a bit more frightening... It gave the reader access to his insane mind.
Being or amounting to a single unit or individual or entire thing, item, or object rather than two or more; a single
D, or the 4th one. It combines the sentences effectively, without overusing words.
Handled and scare are the verbs and gently is the adverb.