Step 1: Locate the regions mentioned
We need to find a state that borders all three countries — Bhutan, China, and Nepal.
Step 2: Analyze each option
Sikkim: Shares borders with Bhutan to the east, China (Tibet) to the north and northeast, and Nepal to the west.
Arunachal Pradesh: Borders China and Bhutan but not Nepal.
Jammu and Kashmir: Borders China but not Bhutan or Nepal.
Uttarakhand: Shares borders with China and Nepal, but not Bhutan.
Step 3: Conclude
Only Sikkim borders all three nations.