Step 1: Understanding the rupee.
The rupee is used as the currency by multiple countries in South Asia.
Step 2: Analyzing the options.
(A) India: Indian Rupee (INR).
(B) Nepal: Nepalese Rupee (NPR).
(C) Pakistan: Pakistani Rupee (PKR).
(D) All of these: Correct — all three countries use rupee as their official currency.
Step 3: Conclusion.
Thus, the correct answer is All of these.