Option 1 -> Rs. 50 is the fixed cost, not the marginal cost of the 8th unit.
Option 2 -> Change in TC from 5 to 8 units = 850 - 310 = Rs. 540 for 3 units. Average MC = 540/3 = Rs. 180 per unit.
Option 3 -> Rs. 270 would be incorrect as it doesn't match the calculation from the given data.
Option 4 -> Rs. 540 is the total change in cost for 3 units (6th, 7th, 8th), not the marginal cost of just the 8th unit.
Hence, Option 2: Rs. 180 -> Marginal cost is the additional cost of producing one more unit. From the data: TC at 8 units = Rs. 850, TC at 5 units = Rs. 310. Change in total cost = 850 - 310 = Rs. 540 for producing 3 additional units (6th, 7th, and 8th). Assuming constant marginal cost over this range, MC = 540 ÷ 3 = Rs. 180. Therefore, the marginal cost of producing the 8th unit is Rs. 180. -> correct