Which of the following statements accurately summarizes most military actions during the early years of World War I?
A. though new technology was available, military leaders refused to abandon older weapons.
B. Though huge numbers of people were killed, no country managed to conquer much territory.
C. Though military leaders preferred fighting on two fronts, most battles took place on one front.
D. Though trench warfare reduced the threat of disease, it greatly weakened armies' defensive positions.