is cystic fibrosis infectious?

So here's a question that I encountered:

A child who has leukemia is being admitted. Several rooms are available on the pediatric floor. Which of the following clients should the nurse place in the same room with this child?

a. A child who has nephrotic syndrome
b. A child recovering from ruptured appendix
c. A child who has rheumatic fever
d. A child who has cystic fibrosis

The answer is A, which I totally agree too because it is not an infectious disorder. However, cystic fibrosis is not an infectious disorder either. Cystic fibrosis is a recessive genetic disease, and it is not contagious. Please correct me if I'm wrong, for I don't get the rationale of why cystic fibrosis is not a correct answer as well

This was from ATI btw.

Thanks