Notice this study used the verbal answer from each subject to measure the cocaine use status after six weeks of treatment. It has been argued that verbal reporting of cocaine use will cause subjects to lie (and say they used less than they really did) and this will create an underestimate of cocaine use status. If everyone under reported their cocaine use status, this would make the researcher's estimate of cocaine use status a(n)__________________ estimate

	a.	reliable
	b.	unreliable
	c.	biased
	d.	unbiased