Which Statement Describes a Function of the Addition of Methyl

Which statement describes a function of the addition of methyl groups to DNA?

A) Methylation is used by E. coli as part of a defense mechanism to distinguish its DNA from foreign DNA.
B) Methylation serves as a marker during repair of DNA during replication.
C) Methylation of DNA occurs in some animals when infected with certain bacteriophages.
D) All of the statements describe a function of DNA methylation.
E) None of the statements describes a function of DNA methylation.