Why was the use of pure-breeding lines important in Mendel's pea experiments?

Correct answer: So that the inheritance pattern of traits could be observed clearly

A pure-breeding line produces offspring with the same form of a trait generation after generation because it is genetically uniform for that characteristic. Mendel could therefore begin a cross with known parental forms and attribute differences in the offspring to the cross rather than to unknown variation in the parents. This made dominant and recessive inheritance patterns easier to detect. Option A is correct; the other choices contradict the purpose of controlled breeding.