Answer:
D Organ
Step-by-step explanation:
A group of tissues that work together to carry out a specific function is known as organ.
Life is organized into distinct levels. These organization makes it possible for certain cells which are the basic unit of life to carry out their respective function.
A group of cell that performs the same function are organized into tissues. A group of tissues that work together to carryout a specific function are known as organs. A group of organs that perform the same functions forms the organ systems.
As the complexity of an organism increases, so also is their organization of life.