The Presence or Absence of Hair on the Mid-Digital Region

Multiple Choice

The presence or absence of hair on the mid-digital region of a finger is determined by a single autosomal gene. The presence of hair is dominant to the absence of hair. In the pedigree below, shading represents the presence of mid-digital hair.
If the parents have a 5th child, what is the probability that it will have mid-digital hair?

A) 1/2
B) 2/3
C) 3/4
D) 1/3
E) 1/4