How Might a Single Base Substitution in the Sequence of a Gene

How might a single base substitution in the sequence of a gene affect the amino acid sequence of a protein encoded by the gene,and why?

A) A single amino acid could change, but the reading frame is unaffected.
B) The amino acid sequence would be substantially altered, because the reading frame would change.
C) All amino acids following the substitution would be affected, because the reading frame would be shifted.
D) It is not possible for a single base substitution to affect protein structure, because each codon is three bases long.
E) There would be no impact, as two or three base pairs must change to result in a change at the amino acid level.