Correct option (a) These are all unicellular protists
Explanation:
Trypanosoma, Noctiluca, Monocystis and Giardia are all unicellular protists. Trypanosoma gambiense is the single-celled, parasitic zooflagellate causing trypanosomiasis or sleeping sickness. Giardia or the 'Grand old man of the intestine' is a parasitic flage late occurring in the intestine of man and other animals and causes giardiasis or diarrhoea (i.e. very loose and frequent stool containing the large quantity of fat).
Noctiluca is a marine, colourless dinoflagellate. It is a voracious predator and has a long, motile tentacle, near the base of which, its single short flagellum emerges.
Monocystis is a microscopic, unicellular endoparasitic protozoan found in the coelom and seminal vesicles of earthworm. As it is an endoparasite, it does not possess any special structure for locomotion.
