Consider four variables: X, Y, M, and Z. The causal statements are: 1. X affects M. 2. M affects Y. 3. Z affects both X and Y. 4. Y does not affect Z. 5. X does not affect Z. Assume there are no other direct paths. Consider these claims: 1. Z is a confounder of X → Y. 2. M is a mediator of X → Y. 3. Z lies on a backdoor path from X to Y. 4. Conditioning on M blocks the total effect of X on Y.