Roommate negotiations can be tricky! Read the sticky notes left around the apartment and select ALL the sentences that use the correct modal verbs for the situation.
The correct answers are You mustn't feed my pet tarantula; she is on a very strict diet! and You don't have to iron my superhero cape; I like it a little wrinkly.
Mustn't means "do not do this" (it's a bad idea or against the rules).
Don't have to means "it is not necessary" (but you can if you really want to).
Leaving the stove on is dangerous, so it should be a strong "mustn't." Buying toilet paper isn't forbidden, just unnecessary, so it should be "don't have to."