GMAT Sentence Correction (SC) | SC question from GMAC test

The success of the program to eradicate smallpox has stimulated experts to pursue WHAT THEY HAD NOT PREVIOUSLY CONSIDERED POSSIBLE - BETTER CONTROL, IF NOT ERADICATION, OF THE OTHER INFECTIONS SUCH AS measles and yaws
1) what they had not previously considered possible - better control ,if not eradication, of the other infection such as
2)what they had not previously considered a possibility - better control, if not eradication, of such infections like
3) something they had not previously
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