Which of the following is a good definition?

Question

A: You are a teenager if and only if you are 15 years old.

B: You are 15 years old if and only if you are not an adult.

C: You are 13 to 19 years old if and only if you are a teenager.

D: You are not a teenager if and only if you are less than 13 years old.

My choice is C

Answer 1

I agree.

Answer 2

Thank you very much!

Answer 3

You're welcome.