Questions: Two alligators are heterozygous for albinism (Aa). The dominant allele (A) codes for normal pigmentation, and the recessive allele (a) codes for no pigmentation. What percentage of their offspring would have an albino phenotype?

The answer is the first one: 25%.

Explanation:

1. Both alligators are heterozygous for albinism, meaning their genotype is Aa.

2. To determine the possible genotypes of their offspring, we can use a Punnett square:

      A   a
   A  AA  Aa
   a  Aa  aa
   

3. The Punnett square shows the following possible genotypes for the offspring:

   • AA: Normal pigmentation
   • Aa: Normal pigmentation (carrier of the albino allele)
   • Aa: Normal pigmentation (carrier of the albino allele)
   • aa: Albino phenotype

4. Out of the four possible genotypes, only one (aa) results in an albino phenotype. Therefore, the probability of an offspring being albino is 1 out of 4, or 25%.

5. The other options are incorrect:

   • $100 \%$: This would mean all offspring are albino, which is not the case.
   • 75\%: This would mean three out of four offspring are albino, which is incorrect.
   • Q\%: This is not a specific percentage and does not apply here.

In summary, 25% of the offspring would have an albino phenotype.