In the context of biotechnology, what does "genetic engineering" refer to?

The choice indicating that "genetic engineering" refers to altering the genetic material of organisms is accurate because this term specifically denotes techniques used to modify an organism's DNA. This can involve adding, deleting, or modifying genes to change characteristics or traits. Genetic engineering encompasses a wide range of methods, including CRISPR technology, gene cloning, and transgenic techniques, all aimed at achieving specific genetic modifications to improve agricultural practices, enhance food security, or produce pharmaceuticals.

In contrast, the other options refer to concepts that are either broader or not directly related to the intentional modification of genetic material. For example, natural selection of traits involves evolutionary processes rather than deliberate human intervention. Cloning of genes is a specific technique within genetic engineering but does not encompass the entire scope of altering genetic material. Lastly, the study of genetic variation is a fundamental aspect of genetics but does not imply the active modification of genetic sequences that defines genetic engineering.