Which of the following weapons helped continue the stalemate on battlefields during World War I a] the tank
b] the submarine
c] the fighter plane
d] the machine gun

The answer to this is D machine gun.

Explanation:

The machine gun allowed soldiers to rapid-fire bullets at the enemy at a rate of 400 to 600 rounds per minute. This allowed defenders the ability to dominate the battlefield and cause the death of advancing enemy soldiers.

I think It was the tank

Explanation:

the first prototype was created in 1916

using the media to encourage public support for an idea.

encouraging congress to take action

establishing a public policy goal for the nation