What is an organ?

• A. Tissues are groups of similar cells that form a basic unit.
• B. A group of tissues that perform a single function.
• C. A group of organs working together with a specific function.
• D. Ethics is the discipline dealing with moral duties.

Answer: (B)

Understanding how the body is organized into levels: cells form tissues, tissues form organs, and organs form organ systems. An organ is a structure made up of different tissues that work together to perform a specific function. This idea fits best because it highlights that the function comes from multiple tissues collaborating within one structure, like the heart, which uses muscle tissue, connective tissue, and nerve tissue to pump blood.

Other ideas describe related concepts but not what an organ is: one describes tissues as the basic unit (which actually refers to tissues, not an organ), another describes a group of organs working together (an organ system), and a separate option is unrelated ethics.