Which of the following statements accurately summarizes most military actions during the early years of World War I?

Athough new technology was available, military leaders refused to abandon older weapons.

BThough huge numbers of people were killed, no country managed to conquer much territory.

CThough military leaders preferred fighting on two fronts, most battles took place on one front.

DThough trench warfare reduced the threat of disease, it greatly weakened armies' defensive positions.