Enlist four main features of organisms placed in the kingdom Protista.

(N/A) They are unicellular and primarily aquatic organisms.
$(b)$ They possess a typical eukaryotic cell structure with membrane-bound organelles and a well-defined nucleus.
$(c)$ Locomotion is facilitated by structures such as cilia,flagella,or pseudopodia.
$(d)$ Reproduction occurs through both asexual (e.g.,binary fission) and sexual (e.g.,syngamy) methods.