In a prospective cohort study conducted in western Europe, a rate ratio of 1.41 was reported for the association of any exposure to glyphosate (a broad-spectrum herbicide in Roundup, compared to no exposure to glyphosate) and incident cancer in adults. Twenty-six percent of cohort members were lost to follow-up over the course of the study. If participants with any glyphosate exposure who developed cancer were more likely to be lost to follow-up than were participants with no glyphosate exposure who developed cancer, the observed rate ratio of 1.41 would be (assuming no other source of bias and no confounding):

	a.	an overestimate of the true association (upward bias).
	b.	an underestimate of the true association (downward bias).
	c.	the same as the true association (no bias).