Which of the following individuals must file a tax return in 2017?

a. Carolyn is single and age 66. She receives $2,000 of interest income, $3,000 of dividend income, and $6,000 in Social Security benefits.

b. Tim is single, age 18, and a full-time student. He is claimed as a dependent on his parents’ tax return. Tim earned $2,000 from a part-time job and $400 in interest income.

c. Justin is single, age 25, and a full-time graduate student. He earned $8,750 from a part-time job.