Correct Answer: Sahara

Solution : The correct answer is Sahara .

The Sahara Desert is the largest in the world, and it is in the northern part of Africa. It spans across 10 countries Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, and Tunisia. It covers nearly 31% of the total land area of Africa. The Great Green Wall is being constructed in the Sahel region of Africa to counter the further expansion of the Sahara desert.