According to United States Air Force officials, a cannon shooting dead chickens at airplanes has proved helpful to demonstrate what kind of damage can result when jets fly into a flock of large birds.

(A) shooting dead chickens at airplanes has proved helpful to demonstrate
(E) that shoots dead chickens at airplanes has proved helpful in demonstrating
[spoiler]
OA - E Please explain why A is wrong. Rest were clear eliminations[/spoiler]