The correct answer is Sikkim.

Sikkim is a strategically located state in Northeast India that acts as a land bridge between India and its neighbors. It is the only Indian state that shares international borders with three different countries:

To the North: China (Tibet Autonomous Region)

To the West: Nepal

To the East: Bhutan

Why the other options are incorrect:

Arunachal Pradesh: Shares borders with Bhutan, China, and Myanmar (but not Nepal).

Uttarakhand: Shares borders with Tibet (China) and Nepal (but not Bhutan).

Himachal Pradesh: Shares a border with China (but not Nepal or Bhutan).

Quick Facts about Sikkim:

Siliguri Corridor: Sikkim is located just north of the "Chicken's Neck," the narrow strip of land that connects mainland India to the northeastern states.

Mountain Peaks: It is home to Kangchenjunga, the third-highest mountain in the world, which sits on the border between Sikkim and Nepal.

Passes: The famous Nathu La pass connects Sikkim with China's Tibet Autonomous Region.