In the Section "Investigating Life: Does Natural Selection Maintain Cystic

In the section "Investigating Life: Does Natural Selection Maintain Cystic Fibrosis?",what hypothesis were the scientists testing?

A) Defects in CFTR cause cholerA.
B) Defective CFTR makes people more sensitive to cholera.
C) Defective CFTR gives people natural resistance to cholera.
D) Cholera causes cystic fibrosis.
E) Cholera increases the risk of transmission of cystic fibrosis.