Final answer:
The genotypic ratio for offspring of two heterozygous individuals, where a recessive lethal allele is involved, is 1:2:0. This indicates that surviving offspring will only display homozygous dominant or heterozygous genotypes, as homozygous recessive individuals are not viable.
Step-by-step explanation:
The question pertains to genetics, specifically the inheritance of coat color in offspring, considering heterozygous individuals for a recessive lethal allele. To answer the question about the probability that a fourth offspring of two heterozygous individuals will have a golden coat, one must assume the coat color is related to a single gene and the inheritance follows Mendelian principles.
Based on the information given and using a Punnett square, we can determine the genotypic ratio for two heterozygous individuals (Aa) mating. Typically, the offspring genotypes could be AA, Aa, and aa in a 1:2:1 ratio. However, because we are told that there is a lethal recessive allele, aa individuals are not viable and are not expressed in the phenotype. This changes the expected genotypic ratio of surviving offspring to 1:2:0, as the homozygous recessive will not be present. The offspring would only display either the homozygous dominant or heterozygous condition. We can then conclude that the ratio 1:2:0 represents the genotypic ratio for homozygous dominant (golden coat assuming dominant allele confers golden coat), heterozygous, and homozygous recessive (which is lethal and not observed).