Final answer:
The genotype for a heterozygous black, short-tailed hamster is BbSs, which corresponds to answer choice D. BbSS.
Step-by-step explanation:
The genotype for a heterozygous black, short-tailed hamster would include one dominant and one recessive allele for each trait. Since black color (B) is dominant over tan (b), and short tail (S) is dominant over long tail (s), a hamster that is heterozygous for both traits would have one dominant and one recessive allele for color (Bb), and one dominant and one recessive allele for tail length (Ss). Therefore, the correct genotype for a heterozygous black, short-tailed hamster is BbSs, which corresponds to answer choice D. BbSS.