I believe the correct answer is: A. constructing an anxiety hierarchy.
Constructing an anxiety hierarchy is the first step of desensitization technique, which has for a purpose to teach you to do something that is incompatible with the anxiety you feel in your target situation (in Alfred’s case that is claustrophobia). Desensitization technique has three steps:
1. Anxiety Hierarchy
2. Relaxation Training
3. Desensitization Sessions
Constructing anxiety hierarchy is a step in which you construct a list of those situations involved in or leading up to your target situation, in order from the lease disturbing to the most disturbing for you.