Which type of mutation would only affect one amino acidwhich type of mutation would only affect one amino acid?

A missense mutation is the type that would only affect one amino acid in a protein sequence. This occurs when a single nucleotide change in the DNA sequence results in the substitution of one amino acid for another in the corresponding protein. This alteration can potentially impact the protein's function, depending on the role of the altered amino acid. Other mutations, like silent or nonsense mutations, do not affect the amino acid sequence in the same way.