In guinea pigs, the allele for black fur (B) is dominant over white fur (b). A cross of two black guinea pigs produces three offspring, all of which have black fur. What conclusion can be drawn about the genotypes of the two parent guinea pigs of the cross? A. Both parents were homozygous dominant (BB). B. At least one parent was homozygous dominant (BB), but the other parent could be heterozygous (Bb). C. Either parent could be homozygous dominant (BB) or heterozygous (Bb). D. Both parents were heterozygous (Bb). E. At least one parent was homozygous recessive (bb).