What is an organ?

• A. A group of tissues
• B. A single cell
• C. A collection of organs
• D. A macromolecule

Answer: (A)

An organ is a structure formed by different tissues that work together to perform a specific function in the body. Tissues are groups of cells with a common role, and when they come together in an organized way, they create an organ capable of carrying out more complex tasks—like the heart, which relies on muscle tissue to pump, plus connective and nervous tissues to support and control it. That description aligns with the idea of an organ being a group of tissues working in concert. The other options don’t fit: a single cell isn’t enough to form an organ, a collection of organs describes an organ system rather than one organ, and a macromolecule is a large molecule, not a tissue-based structure.