Megan has a one hour gap in her course load for the fall semester. There are two courses available for her to take at that time: reading piano sheet music and beginning rock climbing. She does not have any experience with piano or rock climbing. In the end, she decides to enroll in the rock climbing course, despite her fear of heights. Identify which of the following exhibits a potential trade-off with enrolling in rock climbing:

A. Learning rock climbing skills
B. Learning to read piano sheet music
C. Overcoming her fear of heights
D. None of the above