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.

[Q]: Question: Which kind of muscle regulates air flow in lungs? Answer: smooth
[A]: Smooth muscle regulates air flow in lungs.


[Q]: Question: What occurs when a population reaches the carrying capacity? Answer: growth stops
[A]: Growth stops when a population reaches the carrying capacity.


[Q]: Question: For what kind of animal is communication essential? Answer: social animals
[A]:
For social animals, communication essential.