Final answer:
The question involves genetics and Mendelian inheritance patterns. Given the information, which mirrors Mendel's pea plant experiments, the ratio of colorless to green spheres is most likely 3:1, resembling the dominant to recessive phenotypic ratio observed in F2 progeny.
Step-by-step explanation:
The question appears to be relating to genetics, specifically the patterns of heredity and the ratios of phenotypes in offspring. If we analyze the information given regarding the F1 and F2 generations, we can infer a Mendelian inheritance pattern. The mention of yellow and green seeds, along with the noted ratios, is reminiscent of Gregor Mendel's classic pea plant experiments.
Referring to the last two pieces of information provided, it states that a test cross resulting in a 1:1 ratio of yellow to green offspring indicates a heterozygous parent. Moreover, the self-pollination of the F1 offspring produces F2 offspring with a 3:1 ratio of yellow to green seeds. This suggests that the colorless to green spheres ratio should follow a similar Mendelian ratio, as colorlessness could be analogous to the yellow color, a dominant trait. Therefore, the correct ratio would likely be 3:1, matching option d).