The correct option is
D Zooflagellata/Zoomastigophora
Zooflagellates is a part of kingdom protista. Zooflagellate have spherical, elongated body with
1 central nucleus. They are single-celled, heterotrophic eukaryotes and usually have a symbiotic relationship with other organisms. Zooflagellates have one or more flagellates but there is the absence of cell wall or plastids.Trichonympha is bell-shaped and has thousand of flagella Trichonympha , therefore, belongs to Zooflagellata/Zoomastigophora
So, the correct answer is '
Zooflagellata/Zoomastigophora'