Option 1 -> Rs. 500 would be correct only if 10 units were sold (50 × 10 = 500).
Option 2 -> Rs. 5000 is obtained by multiplying unit tax by quantity (50 × 100 = 5000).
Option 3 -> Rs. 50 is just the unit tax rate, not the total tax paid.
Option 4 -> Rs. 100 is the quantity produced, not the tax amount.
Hence, Option 2: Rs. 5000 -> A unit tax is a fixed tax amount imposed per unit of output produced or sold. To calculate total tax, we multiply the unit tax by the number of units. Here, Total Tax = Unit Tax × Quantity = Rs 50 × 100 units = Rs 5000 -> correct