What Has Enabled the Dramatic Increase in Milk Production in Developing

What has enabled the dramatic increase in milk production in developing countries?

A) refrigerated trucks that make the milkshed irrelevant
B) rising incomes that permit urban residents to buy more milk products and an increase in milk yield per cow
C) genetically modified cows that can produce more milk in harsh conditions
D) global warming that causes more ideal land for dairy farms
E) much more land dedicated to dairy farming