Zaid is required under a $2014$ divorce decree to pay $$500$ of alimony and $$200$ of child support per month for $12$ years. In addition, Zaid makes an additional voluntary payment of $$100$ per month. How much of the total monthly payment amount is deductible by Zaid?

a$.$ $$200$

b$.$ $$600$

c$.$ $$0$

d$.$ $$500$