Final answer:
The correct option is c.
The phenotypic ratio of white animals with dark eyes from a cross between Ggdd and GgDD genotypes is C) 1/4 or 25%, as there is a 25% chance for an offspring to be white and all of those white animals will have dark eyes.
Step-by-step explanation:
Phenotypic Ratio of White Animals with Dark Eyes
To determine the phenotypic ratio of white animals with dark eyes in the offspring from a cross between animals with Ggdd and GgDD genotypes, we need to consider each gene separately and then combine the probabilities.
For body color, with G being dominant for grey and g being recessive for white, the cross between Gg and Gg yields a 3:1 ratio where three-fourths of the offspring will have grey body color (GG or Gg) and one-fourth will be white (gg).
For eye color, since one parent is dd (pale eyes) and the other is DD (dark eyes), all offspring will have one D allele and one d allele, resulting in dark eyes for all, which is Dd.
Since the eye color gene does not affect the coat color, we only look at the coat color to find the fraction of white animals which is ⅔ or 25%.
Given that all offspring will have dark eyes, the full phenotype in question is always white with dark eyes if the animal is white.
We conclude that the answer is C) 1/4, as there is a 25% chance for an offspring to be white (gg) and all of those will have dark eyes (Dd).