Which of These Does Not Contribute to Africa's Frequent Droughts

Multiple Choice

Which of these does not contribute to Africa's frequent droughts?

A) Much farming is done on "marginal" lands subject to frequent droughts.
B) Only about 10 per cent of Africa's land is arable.
C) Overpopulation is a continent-wide problem.
D) The Sahara Desert is extending southward because natural vegetation has been affected by droughts.
E) Leaders have recently been concentrating on the development of family farms.