Which discovery greatly affected the economies of many middle eastern countries?

The discovery of oil

Explanation:

The production of oil in the Middle East first began in Iran, at the beginning of the 20th century. This was particularly important during WWI, as oil was a precious resource. The rest of the Middle East began looking for oil as well, and found it in the 1930s. After WWII, production increased, which led to a rise in exploration. Many countries in the Middle East discovered oil, which greatly affected their economies.

your answer would be (a)

the answer is b: an economic crisis throughout the country.