The correct answers are options A and C.
The Statement A says that the plants, which have a short stem is homozygous for the trait. According to the question, the allele for the short height is recessive. A recessive trait can only be observed, when the dominant allele is not at all present. Hence, the plant must have tt allele, so, the plant having short stem would be homozygous recessive.
The statement C says that the both parents in second generation are heterozygotes. It is given that the parents in the second generation have aa genotype Tt. In this case, both the alleles are different, hence, the parent plants are heterozygotes.
