Mia is required under a 2018 divorce decree, that has remained unchanged, to pay $600 of alimony and $300 of child support per month for 12 years. In addition, Mia makes a voluntary payment of $100 per month. How much of each total monthly payment can Mia deduct in 2019?

a. $100.

b. $300.

c. $600.

d. $700.