In humans, the protein CFTR regulates the components of sweat, digestive fluids, and mucus. Humans can have a normal form of the
gene or a mutated form. Which of the following would provide evidence that the mutated form of the CFTR protein is harmful to humans? A. Both the normal and the mutated form of the CFTR gene can be found in healthy humans.
B. Healthy individuals, with the normal form of the CFTR gene, can pass on a mutated form.
C. Most illnesses have symptoms associated with sweat, digestive fluids, and mucus.
D. Individuals who inherit the mutated form of the gene usually develop serious health problems.
