Ans. B. SilentMutations are permanent changes in DNA sequence. When mutation occur at a single base, are called as point mutations. When no detectable defect is there -Silent mutation, occurs due to degeneracy of Genetic Code. When a different amino acid is incorporated into a protein-- Missense mutation. When a terminating or stop codon is there-- Nonsense mutation. Frame shift mutation occurs when insertion or deletion of nucleotide from coding strand results in altered reading frame in mRNA.