Answer: the first one
Explanation: the rest are very wasteful :)
Next, Mendel took the F1 progeny and allowed them to self-fertilize. In the resulting F2 generation, 3/4 showed the dominant phenotype, and 1/4 showed the recessive phenotype. ... 1 out of 3 round pea plants from the F2 generation were true-breeding and produced only offspring with round peas.
There should be 3 genes involved in the seven phenotypic categories