Q: In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Which of the following is not a natural landmark: the Volga, the Urals or the USSR?, Context: The economy of Russia became heavily industrialized, accounting for about two-thirds of the electricity produced in the USSR. It was, by 1961, the third largest producer of petroleum due to new discoveries in the Volga-Urals region and Siberia, trailing only the United States and Saudi Arabia. In 1974, there were 475 institutes of higher education in the republic providing education in 47 languages to some 23,941,000 students. A network of territorially-organized public-health services provided health care. After 1985, the restructuring policies of the Gorbachev administration relatively liberalised the economy, which had become stagnant since the late 1970s, with the introduction of non-state owned enterprises such as cooperatives. The effects of market policies led to the failure of many enterprises and total instability by 1990.
A:
the USSR