Assertion (A): Birds and Mammals have double circulation.
Reason (R): Two separate circulatory pathways are present in birds and mammals where the mixing of oxygenated and deoxygenated blood occurs.
1. Both (A) and (R) are true and (R) is the correct explanation of (A).
2. Both (A) and (R) are true, but (R) is not the correct explanation of (A).
3. (A) is true, but (R) is false.
4. (A) is false, but (R) is true.