Answer:
a. The disease is recessive and only seen in homozygous recessive individuals such as the daughter.
Explanation:
In this example, the disease is caused by a single gene, if this gene is inherited following Mendel's laws, the trait will be dominant or recessive. However, in this case, the parents of the affected girl are both healthy, as the parents of the other two affected cousins. Therefore, the two parents should be heterozygous for this trait (Rr), so they will have 25% of the probability of having a child with the diseases, like this child.
In conclusion, this disease is recessive and only can be seen in homozygous recessive individuals such as the daughter.