Final answer:
Germline mutations, which occur in sex cells, are most likely to undergo mutations as they can be passed on to offspring and affect every cell in the offspring. Somatic mutations, which occur in other cells of the body, have little effect on the organism and cannot be passed on to offspring.
Step-by-step explanation:
Mutations are changes to an organism's DNA and are the most common way to introduce novel genetic variation. Some mutations are harmful and can contribute to diseases like PKU, while others can be beneficial and drive evolution. Genetic information that is most likely to undergo mutations is the germline (sex cells) rather than somatic cells. Germline mutations can be passed on to offspring and every cell in the offspring will have the mutation.