Problem 1) Line n is the line of symmetry (not line o) because we can fold the lower half to match up with the upper half. The folding line is over line n.
Problem 2) I agree. Nice work on getting the correct answer. The folding line is a vertical line through the center
Problem 3) It's hard to say for sure, but I think the top left corner is NOT reflective over any line of symmetry no matter how you rotate it. So I would uncheck that box. I agree with your other choices though. Great job with those.