Answer:
d. 0
Explanation:
Since the condition is caused by a recessive allele, it means each of the parents have two copies of the affected allele for the trait. One copy of an affected allele will be inherited from the father and another affected allele will be inherited from the mother.
Two alleles for the disorder will be inherited each from the either parent. Hence, the odds of having only one allele for the disorder is zero (0)