Which Small-Scale Mutation Would Be Most Likely to Have the Least

Which small-scale mutation would be most likely to have the least negative effect on the function of a protein?

A) a base substitution
B) a base deletion near the start of a gene
C) a base deletion near the end of the coding sequence,but not in the terminator codon
D) deletion of three bases near the start of the coding sequence,but not in the initiator codon