In a disease associated with a nucleotide repeat, anticipation is often noticed in subsequent generations, usually associated with a more severe phenotype. Which of the following is a more likely cause of anticipation?

A) Highly repeated sequences are expressed more often.
B) Children of affected parents receive more attention from physicians than other children.
C) Alleles with a large number of repeats are unstable and change size from generation to generation.
D) The sequences have greater stability in later generations.
E) Family members are exposed to the same mutagens.