Two Healthy Individuals Have a Child Who Has Huntington Disease,an

Multiple Choice

Two healthy individuals have a child who has Huntington disease,an autosomal dominant disease.How did this happen?

A) The mother had two recessive alleles.
B) The mother had one recessive allele and one normal allele,and the father had two normal alleles.
C) The mother had two normal alleles,and the father had one recessive and one normal allele.
D) Each parent had one normal and one recessive allele.
E) The condition could not have been inherited from these two parents.