Answer:
P generation and F2 generation
Step-by-step explanation:
Gregor Mendel performed series of experiments with pea plant to determine the law that governs inheritance. In the parental generation (P-generation), He crossed a truebreeding plant that is dominant for a particular trait i.e. a plant that contains the same dominant alleles in its genotype and a truebreeding plant that is recessive for a particular trait i.e. contains same recessive alleles for the same gene.
He observed that all the offsprings of this cross exhibited the dominant trait in the F1 generation. He then self-crossed the F1 offsprings to yield F2 generation offsprings with both dominant and recessive traits with the ratio 3:1.
Therefore, the recessive trait will be visible in the parent generation (truebreeding recessive parent) and the F2 generation (recessive F2 offsprings). See attached image for detailed cross