((SIMPLE QUESTION 15 POINTS))
A couple has 5 children. One dies after birth from a genetic disease caused by a lethal gene. The mother, the father, and 3 of the other children have this gene, but not the disease. Why don't they have the disease?
a)They only have one dominant lethal gene
b)They only have one recessive lethal gene
c)They have the same blood type
d)They have X-chromosome