**Correct option (D) 4921 **

**Explanation:**

P = Rs. 64000, n = 3 years

R = 2.5 paisa per rupee per annum

= (2.5 × 100) paisa per hundred rupees per annum.

= (2.5 x 100/100) percent per annum.

= 2.5% per annum.

Amount after 3 years = Rs. 64000 (1 +2.5 x 100)^{3}

= (Rs, 64000 x 41 /40 x 41 x 40 x 41/40)

= Rs. 68921

Compound interest payable after 3 years

= Rs. 68921 – Rs, 64000

= Rs, 4921