We require one word that can fit into all four blanks with a consistent and logical meaning.
In sentence A — "The men there have fought ............. and emotional withdrawal..." — the pairing with "emotional withdrawal" suggests a state of sadness or loss of spirit. "Dejection" fits perfectly here as it refers to low spirits and lack of enthusiasm.
In sentence B — "But ............. does occasionally inflict all the adults." — this implies that a state of unhappiness or despondency can sometimes affect everyone. "Dejection" is appropriate here, as it is an emotional condition that can impact a group.
In sentence C — "A person who is deeply hurt feels very ............." — again, the feeling of being cast down in spirit is best expressed with "dejected," which comes from "dejection."
In sentence D — "It is hard to survive this feeling of ............." — the reference to "this feeling" confirms the context of ongoing low morale or sadness, reinforcing that "dejection" is the right fit.
Other options fail to fit all contexts: "lonely" is too narrow, "trouble" is too general, and "depression" is medical in tone and less natural in some sentences.
Thus, "dejection" is the correct choice for all four blanks.