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.