In the 17th century, British biologist Robert Hooke discovered the cell. A little more than a century later, French botanist René Henri Dutrochet concluded that all living things arise from cells, and all cells are derived from other cells. Dutrochet's proposal indicates that —

A
cells are the highest level of organization in a living organism.

B
cells are not a level of organization in a living organism.

C
cells alternate between being the highest and lowest level of organization in a living organism.

D
cells are the lowest level of organization in a living organism.