Uranium is a naturally occurring element that is mined in various parts of the world.

Option 1, the United States of America, does produce a significant amount of uranium but is not the leading producer.

Option 3, Germany, and option 4, Zambia, also mine uranium, however, their productions are not as high compared to other countries.

Option 2, Canada, is the correct answer. It has been one of the world`s largest and most important producers of uranium for many years. Canada has the high-quality uranium deposits and the industry expertise to continue to be a leader in the international uranium marketplace.

Hence, while all mentioned nations do mine uranium, Canada is the leading producer among them.