63. Health officials estimate that 35 million Africans are in danger of contracting trypanosomiasis, or "African sleeping sickness," a parasitic disease spread by the bites of tsetse flies.

(A) are in danger of contracting

(B) are in danger to contract

(C) have a danger of contracting

(D) are endangered by contraction

(E) have a danger that they will contract

though, the passive construction in D would be unnecessarily wordy and also imprecise, because it is the disease more than the act of contracting it that poses the danger.

上面的话什么意思，请指教，谢谢！