The probably reason you don't have an answer is that an earlier post said the answer was B(carbon) and that makes no sense. The answer is Boron (A). Here is a link for you to look up the IP for boron.
The electron configuration for B is
1s2 2s2 2p1.
The first electron to be pulled off is the 2p1 and that is the easiest. The next two are approximately the same since both are 2s electrons but considerably higher than the first IP. The second one of any orbital is always higher because it is being pulled off against a more positive charge. The final two are in yet another closed shell and that makes them the highest of all.