F&D asked a number of opinion leaders around the world to answer the question"What’s the single thing most likely to double living standards in poor countries over the next decade?"Here is what they chose:
National ownership of the development agenda
Investment in education
Delivering on promises to meet the MDGs
You should be able to think of reasons why each could be considered instrumental. I know we haven't discussed development proper yet but we have made many in class development related discussions from day one last year and your background in econ is (should be?) good enough to provide at least some reasons for each.
In any case, do check out the article here (page 28)