Final answer:
The energy crisis in the 1970s was primarily caused by increased trade with OPEC. The OPEC member states imposed an oil embargo on the United States and Western Europe in response to their support of Israel in the Yom Kippur War.
Step-by-step explanation:
The energy crisis in the 1970s was primarily caused by the increased trade with OPEC. In response to the West's support of Israel in the Yom Kippur War, OPEC member states, predominantly from the Arabic Middle East, voted to impose an embargo on the United States and Western Europe. This embargo resulted in a shortage of oil and a significant increase in prices, which had a lasting impact on the global economy.