Question

In a certain species of rabbit, the gene for brown fur (B) is dominant

and that for white fur (b) is recessive. A purebred brown rabbit is
crossed with a purebred white rabbit. What percentage of the offspring
are brown

Answer 1

0% because the brown fur is a dominant trait, therefore it'll overpower all white traits.

Answer 2

The percentage of the offspring that are brown would be 100%, because of the allelic relationship between dominant and recessive alleles. Basically since the mode of inheritance is that of complete dominance.