The correct option is D 42.85%
Let us assume that the cost price of the article =Rs.100
Therefore, the merchant would have marked it to Rs.100+75% of Rs.100=100+75=175
Now, if he sells it at no profit or loss, he sells it at the cost price.
i.e., he offers a discount of Rs.75 on his selling price of Rs.175
Therefore, his % discount =75175×100=42.85%