Sentence Correction

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
(B) shooting dead chickens at airplanes has proved itself helpful as a demonstration of
(C) shooting dead chickens at airplanes proves itself helpful as demonstrating
(D) that shoots dead chickens at airplanes proves itself helpful to demonstrate
(E) that shoots dead chickens at airplanes has proved helpful in demonstrating

Why not A and why E

According to me in A shooting and proved are parallel. 'helpful to demonstrate' is better than helpful in demonstrating

Experts please help

ayushiiitm wrote: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
(B) shooting dead chickens at airplanes has proved itself helpful as a demonstration of
(C) shooting dead chickens at airplanes proves itself helpful as demonstrating
(D) that shoots dead chickens at airplanes proves itself helpful to demonstrate
(E) that shoots dead chickens at airplanes has proved helpful in demonstrating

Why not A and why E

According to me in A shooting and proved are parallel. 'helpful to demonstrate' is better than helpful in demonstrating

Experts please help

Two things:

***We want to define the cannon that is helpful.

=> To define something we need to use "that".

See the following examples:

They have invented a device that measures the weight correctly.

=> They have invented a device measuring the weight correctly.----> Does it sound good?

**** Preposition + VerbING: is acceptable form.

B and C can be easily eliminated.

The use if present simple in the option D changes the meaning of the sentence.

Answer is E.

ayushiiitm wrote: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
(B) shooting dead chickens at airplanes has proved itself helpful as a demonstration of
(C) shooting dead chickens at airplanes proves itself helpful as demonstrating
(D) that shoots dead chickens at airplanes proves itself helpful to demonstrate
(E) that shoots dead chickens at airplanes has proved helpful in demonstrating

Why not A and why E

According to me in A shooting and proved are parallel. 'helpful to demonstrate' is better than helpful in demonstrating

Experts please help

IMO E

see, according to GMAT rules "cannon that shoots" is better than "cannon shooting".