Final answer:
Option A: he slowly descended while hanging from the rope.
Step-by-step explanation:
The correct option that completes the sentence in a way that makes the most sense is option A: he slowly descended while hanging from the rope.
This option is the most logical and aligns with the context of the sentence. If the person let go of the top of the rock wall, it would make sense for them to slowly descend while hanging from the rope for safety and control.
For example: If someone is rock climbing and wants to come down from the top of a rock wall, it is common for them to use a rope to lower themselves down gradually and safely.