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.

[EX Q]: Question: The pleura that surrounds the lungs consists of how many layers? Answer: two
[EX A]: The pleura that surrounds the lungs consists of two layers.

[EX Q]: Question: What is the key to the demographic transition? Answer: reduced family size
[EX A]: Reduced family size is the key to the demographic transition.

[EX Q]: Question: The different types of nuclei are referred to as what? Answer: nuclides
[EX A]:
The different types of nuclei are referred to as nuclides.