Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
The four types of tissues make up all the organs of the human body. An organ is a structure composed of two or more types of tissues that work together to perform the same function. Examples of human organs include the skin, brain, lungs, kidneys, and heart. Consider the heart as an example. Figure below shows how all four tissue types work together to make the heart pump blood.


Question: A structure composed of two or more types of tissues that work together to perform the same function is called?
organ
Organ.