What best defines a condensation reaction?

A condensation reaction is defined by the combination of two molecules that results in the formation of a larger molecule while simultaneously losing a small molecule, which is often water. This process is significant in organic chemistry, particularly in the formation of complex molecules such as polymers, esters, and amides. For example, when an alcohol reacts with a carboxylic acid, they form an ester and release water in the process.

The importance of the loss of a small molecule during this reaction is what distinguishes condensation reactions from other types of chemical reactions, such as addition reactions, where molecules combine without losing any atoms. Therefore, the defining characteristic of a condensation reaction revolves around this key aspect of combining molecules while expelling a smaller molecule, confirming that option C accurately describes this chemical process.