What is the exceptlon to the rule that married couples must file jointly to be eligible for aptc?

a. couples married prior to 1982 do not need to file jointly to be eligible for aptc.
b. couples that do not live together do not need to file jointly to be eligible for aptc
c. when a member of the household has sole custody of a minor child, couples do not need to file jointly to be eligible for aptc.
d. in the case of spousal abandonment or abuse, couples do not need to file jointly to be eligible for aptc.