3. Which is incorrect about genomic imprinting?
(A) Imprinting genes show mono-allelic, parent-specific gene expression.
(B) All imprinting genes encode proteins.
(C) It is epigenetically regulated in imprinting control regions (ICR).
(D) ICR is under DNA methylation in the CS position of a cytosine residue, forming 5-methylcytosine (5 mC).
(E) Prader-Willi syndrome is a known imprinting disorder.