Answer:
A. vital capacity
Explanation:
<u>Vital capacity is defined as maximum amount of the air that a human can expel from lungs after the process of maximum inhalation. In other words, its is the volume of the lung which represents the maximum of the total volume which can be exchanged with the air.
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It can be measured by using a wet or a regular spirometer. A normal adult has between 3 to 5 litres of VC. Vital capacity of the human depends on the age, sex, mass, height and ethnicity.
We'll make the alleles: Cc.
C is a healthy parent, and c is the cystic fibrosis (recessive).
If you make a punnett square and the parents are both Cc (healthy), then you would get CC, Cc, Cc, and cc. That cc is a 25% chance that the offspring will have that, which means there is a 25% chance the child will have cystic fibrosis.
Two healthy parents can have a child with cystic fibrosis if both the parents have the dominant allele and recessive allele, if both the parents have heterozygous alleles.
It will become a theory after repeated experimentation
