Which one of the following statements is correct ?

a) If Sally and her husband file jointly then Sally can never be claimed as a dependent by her parents .

b) If Sally and her husband have no taxable income but file a joint return because they are due a refund , Sally cannot be claimed a dependent by her parents .

c) If Sally and her husband have children , Sally can still be claimed as a dependent by her parents if Sally and her husband so not file a joint return .

d) If Sally is under the age of 24 and a full time student then her material status is irrelevant in determining if her parents can claim her as a dependent .