Which phase of sexual reproduction is essential for genetic combination?

The correct answer is fertilization because it represents the crucial step in sexual reproduction where the genetic material from two parents combines to create a new organism. During fertilization, sperm from the male merges with the egg from the female, resulting in the formation of a zygote. This zygote contains a mixture of genetic material from both parents, leading to genetic variation in the offspring. This combination is a fundamental aspect of sexual reproduction, as it allows for the mixing of alleles and traits, contributing to the diversity of a population.

Meiosis, while essential for producing gametes (sperm and egg cells), is not directly responsible for genetic combination in the way that fertilization is. Meiosis does result in genetic variation through processes like crossing over and independent assortment, but the actual combination of genes is finalized during fertilization. Binary fission is an asexual reproduction method that does not involve genetic combination, and regeneration refers to the ability of an organism to regrow lost parts, which is also unrelated to genetic combinations in the context of reproduction.