Cystic Fibrosis Is a Serious Respiratory Disease That Is Caused

Cystic fibrosis is a serious respiratory disease that is caused by the expression of a mutant form of the cystic fibrosis transmembrane regulator (CFTR) protein. Suppose that gene therapy was being used to attempt to treat cystic fibrosis. What biological component would be required for this treatment?

A) a bacterium that contains the mutant form of the CFTR gene in its genome
B) a bacterium that contains the healthy form of the CFTR gene in its genome
C) a virus that contains the mutant form of the CFTR gene in its genome
D) a virus that contains the healthy form of the CFTR gene in its genome