The correct options are
A Bacteria
B Amoeba
D Paramecium
The 3 kingdom classification was introduced by Ernst Haekel. He classified organisms into 3 groups- Plantae, Animalia and Protista.
Kingdom Protista included unicellular organisms like bacteria, amoeba, algae, fungi, paramecium, protozoa etc.
Corals are an example of a multicellular organism which lives in aquatic habitat.