The correct option is B A - Mycota, B - Monera
Decomposers are organisms that feed on dead and decaying organic matter (detritus) and thus release the nutrients back into the environment.
They are also called saprotrophs because they feed on dead and decaying organic matter.
They secrete digestive juices or enzymes that break down the complex organic matter stored in dead and waste material into simple inorganic substances like carbon dioxide, water and nutrients.
They play a very important role in the cycling of nutrients.
Fungi and bacteria are major decomposers of the ecosystem.
Fungi are placed in the kingdom Mycota (Fungi). Bacteria are placed in the kingdom Monera.