Final answer:
In a cross between two individuals with genotypes dd and dd, the phenotypic ratio of the offspring will be 4:0, meaning all offspring will display the recessive phenotype as both parents are homozygous recessive.
Step-by-step explanation:
The question you're asking is related to genetic crosses, which falls under the study of genetics in biology. When crossing two individuals with the genotypes dd and dd, we only have one possible genotype for the offspring (dd), since both parents can only pass on the recessive allele 'd'. The phenotypic ratio, which is the ratio of the observable characteristics, will be uniform for all offspring because they all have the genotype 'dd', which would express the recessive phenotype. Therefore, the correct answer is D) 4:0, with all four offspring displaying the recessive phenotype.
As for the clarification regarding genotypic ratios from other genetic crosses:
- In a mating between two individuals that are heterozygous for a recessive lethal allele (Aa), the expected genotypic ratio is 2:1 because the homozygous recessive offspring (aa) are nonviable and do not survive to be observed.
- When crossing a homozygous recessive (dd) with a heterozygous (Dd) individual, the expected phenotypic ratio of the offspring will be 1 tall: 1 dwarf, since the recessive allele only expresses its phenotype when in homozygous form.