Yes I think D is correct too.
<span>Millet is grown in the Sahel because it is one of the main staples of the people there. It is considered as a vital source of staples. It is also, happened when it is grown with cowpea and sorghum. Fortunately, the risk of complete crop failure decreased.</span>
Governments, federated states, sovereign states.
I hope this is what you mean.
I believe its true, i'm not entirely sure.