The correct option is C Amoeba - Unicellular Organism
Some living things are made of a single cell. These are called unicellular organisms. On the other hand, the living things that are made of many cells are called multicellular organisms. The amoeba and some other microorganisms are unicellular while man, cow, mouse, cockroach, elephants, banyan tree, the onion plant, etc. are all multicellular organisms.