Final answer:
Tina is 10 years old, which is 5 years younger than Jeff who is 15 years old. So, the correct answer is Option A. 10 years.
Step-by-step explanation:
Jeff is 15 years old, and Tina is 5 years younger than Jeff. To find Tina's age, we subtract 5 years from Jeff's age. Therefore, Tina's age is 15 years − 5 years = 10 years.
Option A. 10 years is the correct answer.