Mark and Dora divorced last year on April 1.Ben is their 10-year-old son.Ben lived with Dora after the divorce until August 17.He then moved in with Mark for the rest of the year.Mark's AGI was $75,000, and Dora's AGI was $55,000.Dora's mother stayed with Ben at Dora's house for four days in July when Dora went on a business trip.Ben then stayed at a friend's house for five nights in July.Which of Ben's parents is the custodial parent for purposes of claiming Ben as a qualifying child?

Select one:

a.Ben is not treated as living with either parent in the year of the divorce.

b.Mark is the custodial parent since he had a higher income.

c.Dora is the custodial parent since Ben lived with her for the greatest number of nights.

d.Mark is the custodial parent since Ben lived with him for the greatest number of nights.