The key answer of exercise 2

Molly isn't happy to have Kate in her class because she perceives Kate as potentially being a "spy" for her mother, who is the head teacher at the school. Molly's assumption is that Kate might report back to her mother about the students' behavior or activities in the class, which she views as intrusive or threatening. This perception likely makes Molly feel uncomfortable or uneasy about having Kate in their class.