What is the result of a missense mutation?

A missense mutation refers to a specific type of genetic mutation that results in the substitution of one amino acid for another in a protein. This typically occurs when a single base pair in the DNA sequence is altered, leading to a change in the corresponding codon in the mRNA. Consequently, when the mRNA is translated during protein synthesis, the altered codon encodes an amino acid that is different from what was originally intended.

Option B correctly identifies that a base pair is switched, which is the mechanism underlying a missense mutation. This alteration can affect the protein's structure and function, potentially leading to various biological consequences depending on the specific amino acid change and the role of the affected protein in the organism.

Missense mutations contrast with deletion or insertion mutations, where base pairs are removed or added, thereby shifting the reading frame of the codons. The impact of a missense mutation can range from benign to harmful, depending on how the substitution affects protein function.