What does the term "auto-" generally describe?

The term "auto-" is derived from the Greek word "autós," which means "self." When used as a prefix in various words, it indicates something that is self-acting, self-propelled, or performed by oneself without the need for external assistance. For example, "automatic" refers to processes that occur without human intervention, and "autonomous" describes a degree of self-governance or independence.

The other options do not align with the meaning of "auto-." For instance, "half" pertains to a divided quantity, while "over" indicates excess or something that surpasses a limit. The indication of "both" suggests a duality that doesn't relate to the self-referential nature of the prefix "auto-." Hence, "self" is the most accurate interpretation of the term "auto-."