Which of the Following Is Considered a Reverse Mutation That

Which of the following is considered a reverse mutation that will restore the wild type phenotype?

A) true reversion back to the wild type base sequence
B) mutation to a different base sequence, but one that restores the amino acid sequence in the protein to the wild type sequence
C) a mutation that restores the function of a protein even though it does not restore the base sequence or the amino acid sequence to the wild type
D) all of the choices