Assuming that an AGI limitation does not apply, what amounts of credit for the elderly or the disabled would be permitted in each of the following instances? Allowable Credit a b A single taxpayer eligible for the credit who receives $1.800 of nonfaxable social security benefits Taxpayers filing a joint return for which one taxpayer is eligible for the credit and the taxpayers have received no social security benefits Taxpayers filing a joint return, and both are eligible for the credit and received $3 800 or nontaxable social security benefits C