What term best describes an organism that is genetically identical to another organism?

The term that best describes an organism that is genetically identical to another organism is "clone." A clone is produced through a process called cloning, which can occur naturally or artificially. In the case of natural cloning, organisms can reproduce asexually, creating offspring that share the exact same genetic material as the parent. This is commonly observed in certain plants and single-celled organisms.

In artificial cloning, scientists can use techniques such as somatic cell nuclear transfer to create a genetically identical organism from a single somatic cell. This process has been famously demonstrated with the cloning of Dolly the sheep. Cloning is significant in genetic studies, agriculture, and conservation efforts, as it allows for the replication of specific genetic traits.

The other terms do not convey the same meaning: a hybrid refers to the offspring produced by crossing two different species or varieties, an anomaly denotes a deviation from the norm often indicating a mutation or rarity, and a variant describes an organism with differences in genetic traits compared to others of the same species. Thus, "clone" is indeed the appropriate term for a genetically identical organism.