Correct answer: C). A genetic mutation
A genetic change that takes place in a germ cell and then it is transferred to each cell in the new developing organism is called a hereditary mutation. These mutations are inherited from the parents and it is present throughout life.
It is also called germline mutations. It is known to play a major role in cancer. Even a single germline change may have a greater effect but there is no change in the phenotype.
Hence, the correct answer would be option C.