Q.
A. 1s-1s > 2p-2p > 2s-2p > 2s-2s
B. 2p-2p > 2s-2p > 2s-2s > 1s-1s
C. 2s-2s > 1s-1s > 2s-2p > 2p-2p
D. 2s-2p > 2s-2s > 2p-2p > 1s-1s
E. None of the above
Correct choice: A
Explanation: