What can gene therapies potentially do to treat cystic fibrosis?
a. prevent cells from producing any cftr proteins.
b. make cells produce a functional cftr protein.
c. make cells secrete more mucus.
d. make cells secrete less mucus.

The correct answer is B make cells produce a functional CFTR protein.

Explanation:

Cystic fibrosis is a disease that is caused due to the mutation in the transmembrane protein known as cystic fibrosis trans membrane conductance regulator or CFTR. Cystic fibrosis trans membrane regulator proteins helps in the formation of thin mucus and due to the mutation in CFTR the mucus becomes thick.The disease cystic fibrosis basically affect the respiratory system.

 If gene therapy is used to treat cystic fibrosis then it can replace the mutated CFTR gene with a functional one so that the cell containing CFTR gene can produce functional CFTR protein.

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.