The correct answer to the question "Where is Asan Conservation Reserve located?" is option 2, Uttarakhand.

Option 1, Himachal Pradesh, is incorrect. Asan Conservation Reserve is not located in Himachal Pradesh.

Option 3, Sikkim, is incorrect. Asan Conservation Reserve is not located in Sikkim.

Option 4, Arunachal Pradesh, is incorrect. Asan Conservation Reserve is not located in Arunachal Pradesh.

Therefore, the correct answer is option 2, Uttarakhand. Asan Conservation Reserve is a popular wildlife sanctuary located in the state of Uttarakhand. It is situated near the capital city of Dehradun and is famous for its diverse ecosystem and abundant birdlife. The reserve is spread across an area of approximately 4.5 square kilometers and is home to various species of birds, animals, and plants. It serves as an important habitat for migratory birds and is a popular spot for birdwatching and nature enthusiasts.