In horses, black (b) is the dominant color; brown (b) is the recessive color. consider the cross seen here, between two black horses (bb). what is the probability that these two horses will have a foal that is brown?
a) 0%
b) 25%
c) 40%
d) 50%

The correct answer is 25%.

Black color (B) of horse is a dominant trait over brown (b) color, which is a recessive trait. As we know that dominant gene masks the expression of recessive gene, therefore brown horse color will only be produced in the genpotype bb.

On the other hand, there are two possible genotypes for black horse color that is BB and Bb.

As per the question, parental genotypes are Bb and Bb. When they are crossed, they will produce 25 % foal with brown color (bb).

Refer punnett square.