You are given five variables: X, Y, A, B, and C. The relationships are: 1. X affects Y. 2. A affects B. 3. B affects X. 4. B affects Y. 5. C is caused by both X and Y. Assume no other connections exist. Consider the following claims: 1. B is a confounder for X → Y. 2. C is a collider for X ↔ Y. 3. Conditioning on C would open a new path between X and Y. 4. Conditioning on B fully blocks all backdoor paths between X and Y. Which combination is correct?