The termite gut protist, Mixotricha paradoxa, has at least two kinds of bacteria attached to its outer surface. One kind is a spirochete that propels its host through the termite gut. A second type of bacteria synthesizes ATP, some of which is used by the spirochetes. The locomotion provided by the spirochetes introduces the ATP-producing bacteria to new food sources. Which term(s) is (are) applicable to the relationship between the two kinds of bacteria? 1.mutualism 2.parasitism 3.symbiosis 4.metabolic cooperation