Which of the following kingdom includes only heterotrophic organisms?

Among the five kingdoms, only Fungi and Animalia are exclusively heterotrophic. However, Fungi include saprophytic organisms (absorptive nutrition), while Animalia are characterized by ingestive heterotrophy. The question asks for the kingdom that includes 'only heterotrophic organisms' - Animalia consists entirely of heterotrophs (organisms that cannot produce their own food and must ingest organic matter). Fungi are also heterotrophic but use absorptive nutrition. Given the options, Animalia is marked as the answer, likely emphasizing that all members are ingestive heterotrophs.