What classification best describes a group of cells that perform the same function?

The classification that best describes a group of cells performing the same function is tissue. Tissues are formed when similar cells group together to carry out a specific activity within an organism. For example, muscle tissue is made up of muscle cells that work together to enable movement. This specialization allows the cells to efficiently execute their designated functions, which is a fundamental characteristic of living organisms.

In contrast, an organ is composed of different types of tissues working together to perform a more complex function, such as the heart or lungs. A system is made up of multiple organs that work collaboratively to perform broad functions, like the circulatory system or digestive system. An organism refers to an entire living individual, which is made up of multiple systems, tissues, and organs working together to maintain life. Understanding these classifications is crucial for grasping the organization of biological structures in living things.