Final answer:
There are three years during a person's teenage years where their age is a prime number: 13, 17, and 19.
Step-by-step explanation:
The question asks about the number of years within someone's teenage years in which their age is a prime number. A person's teen years range from age 13 to 19. The prime numbers within this range are 13, 17, and 19. Therefore, there are three years during a person's teen years where their age is a prime number.