Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as a) hybrids. b) the f2 generation. c) monohybrid crosses. d) true-breeding.

(D). true-breeding.

Explanation:

True-breeding can be defined as a type of breeding, in which parents produce offspring with same phenotype as present in parents. In plants, true-breeding takes place only when their is self-fertilization.

These  true-breeding organisms or varieties have a pure genotype (genetic makeup for a trait) and they show only a certain phenotype (physical expression of that trait).

Thus, the correct answer is option (D).