Answer:
The correct answer should be (A) 100%.
Step-by-step explanation:
Since both the bull & the cow are hom0zygous (meaning they each have two identical alleles in their genes) and the black bull possesses the dominant gene, we can assume that our Punnett square should look like the model I attached below. Since "Bb" would contribute to the percentage of black-colored offspring, and all of the squares end up with "Bb", that means that 4 out every 4 offspring will be dark in color. Or, put more simply, the percentage of the offspring that will be black in color is 100%.