Which of the following is a major threat to OPEC?

The major threat to OPEC is the development of viable alternatives to crude oil. This is because OPEC countries heavily rely on revenue from crude oil exports, and if viable alternatives to crude oil are developed, the demand for crude oil will reduce significantly, leading to a decline in revenue for OPEC member countries. As a result, OPEC may have to reduce the price of crude oil to compete with alternative energy sources, which could lead to a decrease in profits for member countries.