A pilot study was conducted in a sample of 30 people to determine the effect of an exercise and diet regimen on body weight after a six month observation period. Each subject's weight was recorded at the beginning of the observation and at the end. Which statistically test should be used to determine whether there was a statistically significant change in weight?

	A.	A one-sample t-test
	B.	A one-tailed t-test for two independent samples
	C.	A two-tailed t-test for two independent samples
	D.	A t-test for dependent samples