Answer:
The correct answer is option B. "both must be tt".
Explanation:
The recessive phenotype of a plant could only be expressed if the two recessive alleles of the gene are present in its genotype. In order to produce pea plants that only have two recessive alleles (tt) both parent plants must be tt. The presence of the dominant phenotype (TT or Tt) in any of the parent plants, would make very likely to have at least one plant, or all of them, with the dominant phenotype.
