Suppose There Is an Association Between Variables X and Y

Suppose there is an association between variables X and Y. Showing empirically that a variable intervenes between X and Y

A) adds to theoretical understanding of the relationship between X and Y.
B) demonstrates that the relationship between X and Y is spurious.
C) weakens the inference that a causal relationship exists between X and Y.
D) weakens the inference that the relationship between X and Y is statistically significant.