What is the fundamental unit of life?

The fundamental unit of life is the cell, which is correctly identified as the answer. Cells are the basic building blocks of all living organisms, meaning that every form of life, whether it's a single-celled organism like bacteria or complex multicellular organisms such as humans, is composed of cells. Each cell functions as a self-contained unit that carries out essential life processes, including metabolism, energy production, growth, and reproduction.

In contrast, atoms represent the smallest unit of matter and are the building blocks of molecules, which in turn form compounds that make up cells. Tissues are groups of similar cells that work together to perform a specific function but are not self-sustaining units on their own. Organs are made up of different types of tissues and are responsible for carrying out particular functions within an organism, but they cannot exist independently without cells. Thus, the concept of the cell as the fundamental unit of life is a central principle in biology, emphasizing its importance in understanding all living organisms.