John and Mary have one kid they call Rusty. John and Mary divorce and their divorce decree is silent as to who claims Rusty. Rusty lives primarily with John but Mary pays child support $($which covers a majority of John's household expenses$)$ as she is the major wage earned.

Who gets the dependency credit $($not a deduction anymore$)?$

a$.$ John, because Rusty spends more time with him

b$.$ Mary, because she is the main wage earner

c$.$ Mary, because John does not pay for more than half the cost of maintaining the household

d$.$ John, because it is his house that Rusty lives in