Answer:
B. a true-breeding plant
Step-by-step explanation:
A true-breeding plant is a plant that produces offspring that are identical or has the same traits from generation to generation when they are self-fertilized. A true-breeding plant is usually two alleles that are identical or the same for a trait, and during a genetic cross, only one allele of a trait can be transferred from generation to generation, and as such, the offspring they produce would display phenotypes that are either homozygous dominant or homozygous recessive to that trait.
Just as stated in the example given in the question, the plant that generates pink flowers upon self-pollination from generation to generation, can be referred to a true-breeding plant.