In Africa, Which of the Following Policies Has Been Most

In Africa, which of the following policies has been most successful at increasing elephant populations?

A) Banning the ivory trade by making the buying and selling of ivory illegal.
B) Making elephants the common property of the people of the country through government ownership and control and making the killing of elephants illegal
C) Allowing private ownership of elephants and making the ivory trade legal
D) When used together, the policies in a and b have been more successful than the policy in c.