In this task, you're given four sentences of a story written in natural language. The given story is not complete and your job is to complete the story by selecting one of the sentence choices from (A) and (B), such that the story sounds fully coherent.
Q: Sentence1: Carl joined the military right after high school. Sentence2: He signed a short contract that put him on the front lines. Sentence3: His best friend was killed in front of him. Sentence4: Happiness became a foreign concept to Carl.
(A) Carl hung out with his best friend when they came home. (B) Carl had to go to therapy for post-traumatic stress disorder.
A:
B