Why did the dwarf trait not appear in the first generation of Mendel’s pure tall and pure dwarf cross?

Correct answer: The dominant tall trait masked the recessive dwarf trait.

Let the dominant tall allele be T and the recessive dwarf allele be t. A pure tall parent is TT and a pure dwarf parent is tt. Every F1 offspring receives T from the first parent and t from the second, giving genotype Tt. Because T is dominant, all F1 plants appear tall, while the t allele remains present but hidden. Therefore option A is correct; the dwarf information was not destroyed or absent.