Final answer:
The United States supplied arms to Israel in the 20th century primarily to create a strategic alliance to counteract Soviet influence in the Middle East, as part of its broader Cold War policy of containing communism.
Step-by-step explanation:
The main motivation for the United States to supply Israel with arms during the 20th century was D) The United States wanted a strategic alliance in the Middle East to counteract the influence of the Soviet Union. This alliance was intended to contain the spread of communism and to maintain a balance of power in the region. During the early stages of the Cold War, the primary goal of U.S. foreign policy was C) to prevent the Soviet Union from spreading communism outside Eastern Europe, especially after the experiences and consequences of World War II. This policy of containment sought to stop the influence and expansion of the Soviet Union which positioned itself as a proponent of communism and supporter of independence movements in other countries to challenge European and U.S. power.
Both the United States and the Soviet Union emerged from World War II as the two remaining superpowers with competing visions for global influence. The U.S. aimed to create and protect democratic governments and free-market economies, which meant forming strategic alliances with nations such as Israel, which could serve as an American foothold in a region deeply affected by geopolitical dynamics.