A merchant marks an article 20% above cost price. Then he sells it at a discount of 20% . The sale gives him ?

Answer: Option B

Let the cost price = 100 unit
Now M.R.P = 120 units
$$\begin{array}{rl}& \text{Selling price}\\ & =\frac{120\times 80}{100}=96\\ & \text{Loss}=100-96\\ & =4\\ & \text{Loss }\%=\frac{4}{100}\times 100\\ & =4\%\end{array}$$