6. Imagine two quantitative variables called "x" and "y." It turns out that the relationship between "x" and "y" is linear. Further, higher levels of "x" tend to correspond with higher levels of "y," and lower levels of "x" tend to correspond with lower levels of "y." This means the relationship between "x" and "y" must be A. strong. B. moderate. C. negative. D. positive. E. weak