Which statement should be revised because it contains a hasty generalization?

Teachers who use videos during instruction are more engaged with their students.
If students are allowed to retake a test once, they are going to expect to retake tests the rest of the year.
Teenagers should be allowed to have free time in the evening, so they should work hard during the school day.
Students who receive a treat as an incentive for completing an assignment will not do any work at all without a treat.