Answer:
b. FBX is a dominant allele.
Explanation:
If Darren's father has the gene for FBX and Darren's mother does not have this gene, but Darem has the disease, it means that the disease is encoded by a dominant allele.
We can draw that conclusion, because as we have seen, the alleles that Darren received from his mother and father responsible for bone development are different, so one is dominant and the other is recessive. Recessive genes are only expressed and homozygous, that is, Darren would only express the gene for bone development if both his father and mother donated recessive alleles.
On the other hand, dominant genes are expressed, even in the presence of a recessive gene. Therefore, we can say that the gene that Darren received from his father is dominant and was expressed even in the presence of the recessive gene, which Darren received from his mother.
