Answer:
This is an English Language question and not Biology.
Here is full question:
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.
A. what they had not previously considered possible -- better control, if not eradication, of the other infections such as
B. what they had not previously considered a possibility -- better control, if not eradication, of such infections like
C. something they had not previously considered possible -- better control, if not eradication, of such infections as
D. something not considered a previous possibility -- better control and perhaps eradication, of other infections such as
E. the possibility of what they had not previously considered possible – better control and possibly eradication of infections like
The answer is C
Explanation:
'What they had not previously considered a possibility' is too specific. It might be pointing to just one possibility. But there are two possible possibilities here, 'something' sounds better.
The action in the past, which was the eradication of smallpox, has triggered something, which was the better control or eradication of other diseases.
Previously, the experts had not considered better control possible, but then this action was triggered by the eradication of small pox. Now the experts are considering better control possible because they have been stimulated to pursue it.