What Is the Most Likely Way a Mutation in One

What is the most likely way a mutation in one gene can convert one body part to another?

A) The mutated gene encodes a protein that affects the expression of many other genes.
B) The mutated gene encodes a protein that determines cell shape.
C) The mutation is in a structural gene and results in production of more protein than usual.
D) A mutation in only one gene cannot convert one body part to another.