Answer:
B. the wedding, the night he asked for her
hand, and the apartment when cactus
arrived
Explanation:
In the flashback, the settings Trysdale ruminated upon in an attempt to unravel the mystery surrounding losing his beloved was the setting of the wedding where he asked for her hand and the cactus arrived.
Trysdale went back in the deep recess of his memory of the wedding night as he mourned the loss of his beloved.