Which of the Following Is True of CFTR Mutations

Which of the following is true of CFTR mutations?

A) Mutations affecting the function of CFTR are always associated with a classic CF phenotype
B) There are clear genotype-phenotype correlations for CFTR mutations
C) Mutations can present as congenital bilateral absence of the vas deferens as the sole phenotype
D) The IVS8 9T variant allele causes classic CF
E) Pancreatic insufficiency is rarely found in people with the DF508 mutation