The correct answer is option 3, Siachen Glacier. Operation Meghdoot was a military operation conducted by the Indian Army in April 1984 to establish control over the Siachen Glacier in the Himalayas. The Siachen Glacier is located in the eastern Karakoram range in the disputed territory of Jammu and Kashmir.
Option 1, Sir Creek, is not the correct answer. Sir Creek is a maritime boundary dispute between India and Pakistan, and Operation Meghdoot was not related to this area.
Option 2, Aksai Chin, is also not the correct answer. Aksai Chin is a region in the western Himalayas that is presently administered by China. The Indian Army did not undertake Operation Meghdoot to establish control over Aksai Chin.
Option 4, Drass Sector, is not the correct answer either. Drass Sector is a region located in the Indian state of Jammu and Kashmir, and it was not the objective of Operation Meghdoot.
In conclusion, Operation Meghdoot was conducted by the Indian Army to establish Indian control over the Siachen Glacier.