Detailed Explanation:

Bihar borders five states: West Bengal, Uttar Pradesh, Jharkhand, Madhya Pradesh, and Nepal (international border).

✅ Uttar Pradesh borders the maximum number of districts in Bihar (17 districts), followed by Jharkhand with 16 districts. Since more than one state borders a significant number of Bihar's districts, the correct answer is Option 4.

Note: West Bengal borders only 3 districts of Bihar (Purnia, Katihar, Kishanganj).