The internal length, breadth and height of a cuboidal room are 12 m, 8 m and 10 m, respectively. The total cost (in Rs.) of whitewashing only all four walls of the room at the cost of Rs. 25 per m2, is:

• A. Rs. 11,400
• B. Rs. 18,000
• C. Rs. 10,000
• D. Rs. 12,600