A plant that has round and yellow seeds (RrYy) is crossed with a plant that has round and yellow seeds (RrYy). What is the ratio of the offspring that will have round and yellow seeds?Key: R = round r = wrinkled Y = yellow y = green

For the RrYy × RrYy cross, the chance of round seeds is 3/4, and the chance of yellow seeds is also 3/4. Assuming the traits assort independently, multiply the probabilities: (3/4) × (3/4) = 9/16. So 9/16 of the offspring are expected to have round and yellow seeds, which is choice D.

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