Answer:
C
Explanation:
Cells are a basic unit of life and that without cells you don't exist as a living being. Also, all the other answers have a flaw in them like in question A... not all cells are the same size. For question B and D... not all cells have the same, parts or organelles since for plants they have chloroplast while animals don't. Eukaryotes have membran- bound organelles and a nucleus while... a Prokaryote doesn't etc...
When humans taste or smell, receptors unique to each nerve cell detect the chemical and send signals to the brain, where many cells process the message to understand what we are smelling or tasting. But a bacterium is just a single cell, and it must use many different receptors to sense and interpret everything around it.