William and Charlotte Collins divorced in November of Year 1. William moved out and Charlotte remained in their house with their 10-month-old daughter, Autumn. Diana, Charlotte's mother, lived in the home and acted as Autumn's nanny for all of Year 1. William provided 70 percent of Autumn's support, Diana provided 20 percent, and Charlotte provided 10 percent. When the time came to file their tax returns for Year 1, William, Charlotte, and Diana each wanted to claim Autumn as a dependent. Their respective AGIs for Year 1 were $50,000, $35,000, and $52,000. Who has priority to claim Autumn as a dependent?

a. William. b. Charlotte. c. Diana. d. They must negotiate amongst themselves.