Fact 1: Cells are the microscopic building blocks of organisms.

Fact 2: Any living being is an organism.

Given the two facts above, answer the question "What are the cells of living beings called?" with the following options: 
- organs
 - Microscopic organisms
 - sub-units of species
 - microscopic building blocks
 - epidermis and dermis
 - cell walls
 - organisms
 - female sex cells


 

    microscopic building blocks     