Although suzanna desperately wants to learn how to dive, she refuses to practice at the pool because "everyone will be watching me and laugh because i'm the only one who can't do it." her thinking reflects

Her thinking reflects: the Imaginary audience

The imaginary audience is a psychological occurrence where an individual imagines and believes that an imaginary group of people is currently watching what he/she is doing.

This is very common in young teenagers, the age when they started to grew and seek the approval of other people.