If two hybrid tall pea plants are crossed, why can dwarf plants appear again?

Correct answer: A dwarf plant can result when it receives a recessive allele from both parents.

Let T represent the dominant tall allele and t the recessive dwarf allele. A hybrid tall plant has genotype Tt. In the cross Tt × Tt, the possible combinations are TT, Tt, Tt, and tt. The tt offspring receive the recessive allele from both parents and therefore show the dwarf phenotype. Thus option A is correct; tallness is not destroyed and the environment does not create this inherited combination.