Final answer:
Crossing F1 round-seeded plants (Rr) with true breeding round-seeded plants (RR) results in no wrinkle-seeded plants in the next generation, as round seeds are dominant.
Step-by-step explanation:
If you cross the F1 generation round-seeded plants with a true breeding strain of round-seeded plants, you would expect to obtain no wrinkle-seeded plants in the next generation. This is because the F1 generation plants would be heterozygous (Rr), having received one round allele (R) from the true-breeding round parent and one wrinkled allele (r) from the true-breeding wrinkled parent. The true breeding strain of round-seeded plants would have the genotype RR. Therefore, when you cross Rr with RR, all of the offspring would receive at least one R allele, resulting in round seeds only due to the dominance of the round seed trait over the wrinkled seed trait.
In pea plants, the round seed trait (R) is dominant over the wrinkled seed trait (r). When crossing round-seeded plants obtained in the F1 generation with a true-breeding strain of round-seeded plants, we can expect that all the plants in the next generation would have round seeds.
This is because when you cross a round-seeded plant (RR or Rr) with a true-breeding strain of round-seeded plants (RR), all the offspring will inherit a round seed allele. Since the round seed trait is dominant, it will always be expressed when present.
Therefore, the answer to your question is (d) all.