Consider six variables: X, Y, L, M, N, and Z. The statements: 1. L affects both X and Y. 2. X affects M. 3. M affects Y. 4. N affects M and is also caused by Y. 5. Z is caused by L and affects X. Consider these claims: 1. L is definitely a confounder for X → Y. 2. Z is part of a backdoor path for X → Y. 3. N is a collider on the path M ← N → Y. 4. Conditioning on M would block the total effect of X on Y. Which combination is correct?