What type of reaction is indicated by the complete transfer of electrons?

A redox reaction, or reduction-oxidation reaction, is characterized by the complete transfer of electrons between reactants. In this type of reaction, one substance loses electrons (oxidation) while another gains electrons (reduction). This transfer of electrons is crucial as it changes the oxidation states of the involved elements.

In contrast, an acid-base reaction typically involves the transfer of protons (H⁺ ions) rather than electrons. Precipitation reactions involve the formation of an insoluble product from soluble reactants, and combustion reactions refer specifically to reactions where a substance reacts rapidly with oxygen and produces heat and light, often generating carbon dioxide and water as products. Therefore, the defining feature of electron transfer is what clearly categorizes the process as a redox reaction.