Ecologists have traditionally categorized the roles of organisms in ecosystems into three broad categories that include select one: a. producers. b. consumers. c. decomposers. d. all of these are correct.

I think the answer is D all the above are collect.
Organisms in natural community play different roles within the ecosystem, organism role depends on how it obtains food. The way in which an organism obtains food also affects its interaction with other organisms in the ecosystem. Producers are organisms that are able to make their own food using a biotic elements in the ecosystem e.g plants. Consumers on the other hand must obtain their energy by eating or consuming other organisms i.e they cannot make their own food. Decomposer is an organism that consumes and breaks down dead organisms or waste matter into simple substances.. they feed on decayed matter and waste left behind by consumers