Underneath Trumps tone is to tone is to turn blacks against him because all the charities he's listing are majorily effecting black people. So if obama does not take the challenge, trump will come back and say that obama does not care about his own people which some of us have already concluded.
If obama does take the challenge (which he won't) he will reveal that he wasn't born here which is not, or should not be new news either to any thinking person.
THe idiodic thing about Trump though is that they already tried this the first term with his Birth Certificate and obama didn't bend, so?