The Pedigree Below Shows the Segregation of an Autosomal Recessive

Multiple Choice

The pedigree below shows the segregation of an autosomal recessive trait in humans. Unless there is evidence to the contrary, assume that individuals who marry into the family do not carry the recessive allele. If IV-1 and IV-2 marry, what is the probability that their first child will have this trait?

A) 1/12
B) 1/16
C) 1/24
D) 1/36
E) 1/8