Which type of reproduction requires two organisms to produce a third organism?

Sexual reproduction is characterized by the involvement of two distinct organisms, typically involving gametes (sperm and egg) from each parent that fuse during fertilization to form a new organism. This process ensures genetic diversity as the resulting offspring inherit a combination of genes from both parents, contributing to varied traits within a population. This type of reproduction includes mechanisms such as pollen transfer in plants and copulation in animals.

In contrast, asexual reproduction, binary fission, and budding do not require two organisms. Asexual reproduction involves a single organism producing offspring that are genetically identical to itself. Binary fission is a specific form of asexual reproduction primarily seen in prokaryotic organisms, where a single cell divides into two identical cells. Budding is another asexual process where a new organism develops from an outgrowth or bud on the parent organism and eventually detaches. None of these processes involve the genetic contribution from two organisms, which is the hallmark of sexual reproduction.