A breeder of black Labrador puppies notices that in his line a gene predisposing his dogs for white spots has arisen. He believes the white spot allele is autosomal recessive, and he wants to prevent it from continuing in his dogs. He sees that one of his female dogs, Speckle, has white spots, and he therefore assumes she is homozygous for the gene. But he must determine which males in his pack are heterozygous to avoid breeding them in the future. What is a reasonable plan?

(A) Stop breeding Speckle.
(B) Pair Speckle with a male with white spots.
(C) Perform a test cross of Speckle with a black Labrador male. If any pups are born with white spots, stop breeding that male because he is heterozygous.
(D) Breed Speckle with a chocolate Labrador