单选题
编号：2445620
1.What does the new study by the two universities say about recent crop improvement efforts?
- A.They fail to produce the same remarkable results as before the 1980s．
- B.They contribute a lot to the improvement of human food production．
- C.They play a major role in guaranteeing the food security of the world．
- D.They focus more on the increase of animal food than human food grains．