Right answer is (a) Rs. 450
The best explanation: The length of drain = 5m.
Width of drain as per figure = 0.5m.
Depth of drain as per figure = 0.4m.
Total quantity = 5 * 0.5 * 0.4 = 1 cum. As per the question, cum excavation rate is 450%.So the total cost required for excavation of drain is = 1 * 450 = Rs.450.
Therefore, the answer is Rs. 450.