15. Which of the following taxpayers may file as a head of household in 2019?

Marco provides all o f the support for his mother, Sienna, who lives by herself in an apartment in Fort Lauderdale. Marco pays the rent and other expenses for the apartment and properly claims his mother as a dependent.

Tammy provides over one-half the support for her 18-year old brother, Dan. He earned $4,200 in 2019 working at a fast-food restaurant and is saving his money to attend college in 2020. Dan lives in Tammy's home.

Juan's wife left him late in December of 2018. No legal action was taken and Juan has not heard from her in 2019. Juan supported his 6-year-old son, who lived with him throughout 2019.

a. Tammy only

b. Juan only

c. Marco and Juan only

d. Marco, Tammy, and Juan

Please explain the answer