Which of the Following Was Useful in the Identification of the Gene

Multiple Choice

Which of the following was useful in the identification of the gene that causes cystic fibrosis (CF) ?

A) observation of independent assortment of PON and CF
B) sequencing of the complete human genome
C) identification of another trait that is often inherited with CF
D) comparison of karyotypes of affected and unaffected individuals
E) chorionic villus sampling