Flashback is the going back to the time in the past which was set before the present scene. Flashbacks provide the extra crucial information from the past to the current situation. They are a character's thinking or reminiscing of the times gone by. Passages 12 and 2 deal with the characters thinking back tro the times they had experienced or done. So, flashback will be matched with passage 1 and 2.
Flash-forward is the exact opposite of flashback. It represents the occurrence or presentation of scenes yet to come or expected to happen in the coming future scenes. Passage 3 reveals/ deals with what is to happen or to be expected in the future ("<em>Let me behold what I shall be in the days to come</em>") . This will be paired with passage 3.
Palpable means that something can be felt or touched. In the short story "the dank tropical night that was palpable as it pressed its thick warm blackness in upon the yacht". The answer is D.