Which Statement Expresses Accurately the Genetic Implications of Cystic Fibrosis

Which statement expresses accurately the genetic implications of cystic fibrosis (CF) ?

A) If it is present in a child, both parents are carriers of this defective gene.
B) It is inherited as an autosomal dominant trait.
C) It is a genetic defect found primarily in nonwhite population groups.
D) There is a 50% chance that siblings of an affected child also will be affected.