Among the four options given, the Gobi desert is the largest. Although the provided answer is generally correct, it would be helpful to understand why the other options are not the largest deserts in the world.

1. Australian desert: While the Australian desert is indeed one of the largest in the world, it is not the largest among the options given. The Great Sandy Desert and the Great Victoria Desert are the two largest deserts within the Australian desert region.

3. Kalahari desert: The Kalahari desert is located in southern Africa and covers parts of Botswana, Namibia, and South Africa. While it is a large desert, it is smaller than the Gobi desert.

4. Atacama desert: The Atacama desert is located in Chile in South America. While it is known as the driest non-polar desert in the world, it is smaller in size compared to the Gobi desert.

Therefore, based on the options provided, the correct answer is option 2, the Gobi desert. It spans parts of China and Mongolia and is considered the largest desert among the given choices.