In 2019, Sheryl is claimed as a dependent on her parents' tax return. Sheryl did not provide more than half her own support. What is Sheryl's tax liability for the year in each of the following alternative circumstances?

b. She received $5,400 of interest income from corporate bonds she received several years ago. This is her only source of income. She is 16 years old at year-end.

c. She received $5,400 of interest income from corporate bonds she received several years ago. This is her only source of income. She is 20 years old at year-end and is a full-time student.

d. She received $5,400 of qualified dividend income. This is her only source of income. She is 16 years old at year-end.