The length and breadth of a rectangular solid are in the ratio $4:3$ and its volume is 2304 cubic cm. The bottom lead-coating costs Tk 10 per sq cm and the total cost is Tk 1920. The dimensions are which of the following?

• a$20 \times 15 \times 7.68$
• b$16 \times 12 \times 12$
• c$12 \times 9 \times 21.33$
• d$24 \times 18 \times 5.33$