WW1 was the first war to abandon the line styles of "Noble Fighting" found in contemporary Europe. In the old style soldiers walked in line and proceed to shoot each other till the other fled or simply all died. In the horrific new war trenches were dug and six machine gunners could hold off and assault of thousands of contemporary linemen. Doing so led to the horror of trench war which was bloody much more violent and dark.
The correct answer is A the first one.
The answer to this question is D or Cuba remained a territory os Spain
It is called the rock cycle! Hope this help!