The correct answer is option 4: Bhutan and Nepal.

Option 1, Asian Pacific Postal Union (APPU) countries, is not applicable for inland postal rates in India. The Asian Pacific Postal Union is a regional organization that aims to promote cooperation and development among postal administrations in the Asia-Pacific region. While India is a member of the APPU, the inland postal rates within India do not specifically apply to all APPU countries.

Option 2, Pakistan and Bangladesh, is also incorrect. While these countries are neighboring countries of India, they are not included in the inland postal rates category. Each country has its own separate postal system, and the rates for sending mail or packages between these countries and India would be considered international rates.

Option 3, Maldives and Sri Lanka, is not included in the inland postal rates for India. Similar to Pakistan and Bangladesh, these countries have their own separate postal systems and would have international rates for sending mail or packages between India and these countries.

Therefore, the correct answer is option 4, Bhutan and Nepal. Inland postal rates in India apply to these neighboring countries, and mail or packages sent between India and Bhutan or Nepal would be subject to these internal rates.