Answer: John will be able to claim Debbie as a dependent.
Step-by-step explanation:
The person who will be able to claim Debbie as a qualifying dependent is John.
The reason for the above claim that John will be the one that will have custody of their child, Debbie is because John provides an equal financial support for his daughter.
Also, Debbie lived with her Dad for eight months and spent the remaining four months with her mother shows that she has lived for more than 6 months with her dad and therefore her dad can claim her as a qualifying dependent.