What is the world's largest landlocked country?

What is the currency used in South Africa? Which landlocked country is the largest in South America? Which landlocked country is home to the ancient city of Samarkand? Which of the following countries is a landlocked country in Southeastern Europe? Which landlocked country in Central Asia has the highest population? Which African landlocked country is known for its diamond mining? Which of the following European countries is landlocked? Which African country is both landlocked and has the highest average elevation?