when something decays that something undergoes decomposition & dead organisms decay ->  when dead organisms decay they undergo decomposition  when dead organisms decay they undergo decomposition & decomposition is when a decomposer breaks down dead organisms ->  a decomposer causes dead organisms to decay  a decomposer causes dead organisms to decay & a microorganism is a kind of decomposer ->  microorganisms cause dead organisms to decay  microorganisms cause dead organisms to decay & if something cause something else to happen then that something is responsible for that something else -> microorganisms are resposible for the decay of dead organisms