Consanguinity Q - anwith

[ArchivalUser]

A woman with cystic fibrosis marries her first cousin. What is the risk that their first child will have CF?

a. 1/2
b. 1/4
c. 1/8
d. 1/16
e. 1/32


plz explain if possible using illustration ?

im really having hard time with these type of questions

[ArchivalUser]

woman with CF means aa, chances to pass on mutant to child is 1/2, and since she marries her cousin ,means he might be carrier too, i.e chance 1/2====>homozygous (aa)+ hetrozygous(Aa) will reproduce 1/2 CF, so female will pass(a) x male 1/2(a) x CF child chances 1/2(aa) = 1/8

Please,correct me if i am wrong.(pardon me, if my explanation sounds lousy, i am sleepy)

Thank you.