During world war 1 the second phase in battles that crossed enemy lines and approached trenches was

Correct

Infantry attack

The second phase of the battles that crossed the enemy lines were the infantry attacks, these attacks managed to attack the enemy trench line often with many losses for the armies.

During the First World War, the Allied army managed to break into the German trench system thanks to the improvement of the tanks, this was known as infantry supported by tanks.

a.that is my answer.

brainliest .

a social contract.

"a social contract is an agreement between citizens and their leader where the citizens give up certain freedoms in exchange for protection. the constitution of the united states is an example of a social contract."