What conditions are required by the central limit theorem before a confidence interval of the population mean may be created?

	A.	The underlying population must be normally distributed.
	B.	The underlying population must be normally distributed if the sample size is 30 or more.
	C.	The underlying population need not be normally distributed if the sample size is 30 or more.
	D.	The underlying population need not be normally distributed if the population standard deviation is known.