The correct option is
B Detrivore
Decomposer is an organism which decomposes dead organic matter. They breakdown organic matter of dead animals and plants and release nutrients in the environment. Detritivores are also called as detritus eaters. They are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal matter). Earthworm is an example of detrivore.
Thus, the correct answer is 'Detrivore.'