Health officials estimate

[sogmat]

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

OA A
Why not B[spoiler][/spoiler]

[amitabhprasad]

"danger of" is an idiom

[logitech]

"danger of" is an idiom

Yeap..I was reading an explanation on Kaplan and it goes like this:

It is an idiom, don't ask WHY, just learn it!