Answer:
Offspring in F1 generation had yellow-seeded pea plants.
Step-by-step explanation:
When Mendel used yellow-seeded and green-seeded pea plants as parents plants he noticed that all of the offspring of the first generation (F1) were yellow-seeded plants. In the next following generation (F2), phenotype ratio was 3:1 (yellow:green).
After this observation Mendel conclude that yellow-seeded plants are dominant over green-seeded plants. Since he used purebred plants, genotypes were:
P: AA x aa
F1: Aa Aa Aa Aa
F2: AA Aa Aa aa
AA and Aa are genotypes for the yellow seeds, while aa is genotype for green seeds.