Which prefix denotes a relationship to both or a pair?

The prefix that denotes a relationship to both or a pair is "bi." This prefix comes from Latin, where it specifically means "two" or "twice." It is commonly used in various terms across different fields, including medicine, biology, and social sciences, to indicate something that involves two parts or is related to a pair. For instance, terms like "bicycle" (a vehicle with two wheels) or "bilingual" (able to speak two languages) illustrate the concept of duality implied by the prefix.

The other prefixes do not convey the same meaning of duality. While "oto" relates to the ear, "anti" denotes opposition or counteraction, and "hyper" indicates excess or above normal. These prefixes indicate different concepts and do not imply a relationship to both or a pair. Therefore, "bi" is clearly the most appropriate choice for indicating a relationship to two or a pair.