Consider a Trait Determined by a Rare Mutation in the Y

Multiple Choice

Consider a trait determined by a rare mutation in the Y chromosome. What is the concordance between male twins? Between fraternal twins that are both male?

A) identical concordance = 1; fraternal concordance = 0
B) identical concordance = 1; fraternal concordance = 1/4
C) identical concordance = 1; fraternal concordance = 1/2
D) identical concordance = 1; fraternal concordance = 3/4
E) identical concordance = 1; fraternal concordance = 1