I believe the correct answer to the question is D. This answer choice makes the most sense given the context. Also, since RNA is less stable than DNA, it mutates more often.
<u>Answer</u>: Cystic fibrosis is a genetic disorder that causes thick mucus secretions.
<u>Explanation</u>:
- <em>Cystic fibrosis</em> is a genetic disorder caused by mutations in a gene that makes a protein called CFTR (cystic fibrosis transmembrane regulator).
- The CFTR protein normally functions as a channel for transport of chloride ions in cells responsible for mucus production.
- A person suffering from cystic fibrosis produces abnormal CFTR protein or no CFTR protein at all.
- This is the reason that thick, sticky mucus is produced instead of the thin, watery kind.