Answer:
<h2>a, the use of trench warfare</h2>
Trench warfare in World War I meant that the armies dug into trenches to hold their ground. But it proved impossible for them to make any advances against each other. If they would try to mount an attack, venturing into "no man's land" between the trenches, they'd get mowed down by machine gun fire. In addition to bullets and artillery fire, trench warfare also came to involve the use of chemical weapons like mustard gas. Trench warfare in World War I was miserable and gruesome.
C. Planned Economy is the answer. A planned economy is an economy in which production, investment, prices, and incomes are determined centrally by a government. It is not a traditional economy because in the question economy is not runed by tradition. A market economy is an economy ran by the people. A mixed economy is ran by the goverment, and the people. the question only says ran by the goverment, and not by the people thats why both of those answers are incorrect.
C economics he was known for a book he made about the wealth of nations
