In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Example input: Question: Which is an example of a renewable energy resource? Answer: Biomass
Example output: Biomass is an example of a renewable energy resource.
Example explanation: The output clearly summarizes the question and answer and hence is correct
Q: Question: When different types of tissues work together to perform a unique function, what do they form? Answer: organ
A:
When different types of tissues work together to perform a unique function, they form organ.