In the traditional grade-of-organization terminology, which grade describes unicellular organisms such as Paramecium, Amoeba and Euglena?

Explanation

Protoplasmic grade is the historical teaching term for a single cell carrying out the organism's functions using specialized organelles. Paramecium, Amoeba and Euglena are unicellular eukaryotes; they are not a modern animal phylum called Protozoa.