Arabian desert is in ____________.
A. Eastern Asia
B. Eastern Africa
C. Eastern Europe
D. Western Asia

Hint: In the region, Turkey has the biggest economy, followed by Saudi Arabia and Iran. As more than half of the world's oil reserves and about 40 percent of the world's natural gas reserves are located in the region, petroleum is the main industry in the regional economy.

Complete Answer:
Nearly all of the Arabian Peninsula is occupied by the Arabian Desert, a large desert region in extreme southwest Asia.
 It is the largest desert region in the world, covering an area of approximately 900,000 square miles (2,300,000 square km), and the second largest on Earth, in northern Africa, surpassed only by the Sahara in size.
Option A. Eastern Asia: A wide desert or brushland area in East Asia is the Gobi Desert.
It includes the northern and northeastern parts of China and the southern portion of Mongolia. Eastern Asia has the Gobi Desert not Arabian desert. Hence, this option is incorrect.

Option B. Eastern Africa: The Eastern Desert is the portion of the Sahara Desert between the river and the Red Sea, situated east of the Nile River. It ranges from the north of Egypt to the south of Eritrea, and also includes parts of Sudan and Ethiopia. Eastern Africa has Sahara Desert not Arabian desert. Hence, this option is incorrect.

Option C. Eastern Europe: There are a variety of semi-arid spots spread across Europe that classify as 'desert' under different geographical concepts, none more undoubtedly than the badlands of south-eastern Spain. There the Desierto de Tabernas is also called "the only desert of mainland Europe." Western Europe has Desierto de Tabernas not Arabian desert. Hence, this option is incorrect.

Option D. Western Asia: The Arabian Desert, a vast desert area in extreme southwest Asia, covers almost all of the Arabian Peninsula. It is the continent's largest desert region, covering an area of around 900,000 square miles (2,300,000 square km), and the second largest on Earth, in northern Africa, exceeded in scale only by the Sahara. Western Asia has Arabian desert. Hence, this option is correct.

Therefore, Arabian desert is in Western Asia. Hence, Option D. Western Asia is the correct answer.

Note: A significant part of the Arabian Desert lies within Saudi Arabia's modern empire. The Arabian Desert borders the Syrian Desert to the north, the Persian Gulf and Gulf of Oman to the northeast and east, the Arabian Sea and Gulf of Aden to the southeast and south, and the Red Sea to the west.