Answer: C) unicellular Explanation: An organism is a living thing, and there are two broad categories of organisms: those made up of only a single cell, and those made up of multiple cells. Single-celled organisms means which contains only one cell are called unicellular organisms. 'Uni-' means 'one,' so the name 'unicellular' literally means 'one cell.'   Examples of Unicellular or Single celled organisms ::   Prokaryotic organisms like Bacteria,... Some algae like green algae, euglena,...

All of these diseases are caused by bacteria i.e. Pneumonia, Cholera, Tuberculosis. Cancer is caused by uncontrolled cell division. Pneumonia is caused by a bacterium Streptococcus pneumoniae. Cholera is caused by a bacterium Vibrio cholerae.