Two normal parents produce a child affected with the autosomal recessive disease homocysteinuria. They want to have 3 more children. You tell them the chance of 1 OR MORE affected among the next three children is:

Zero

Explanation:

Because in a situation whereby both parents are carriers of an autosomal recessive condition there is a 1 in 4 chance of them having an affected child.

Hence, given that these two normal parents have already had one affected child with the autosomal recessive disease homocystinuria. There is ZERO chance of having an affected child in the next three kids they will be having.

i believe it would cause an increase of percipitation, though i could be wrong. so i would say b is the answer.