The Shopkeeper increased the price of a product by 25% so that customer finds it difficult to purchase the required amount. But somehow the customer managed to purchase only 70% of the required amount. What is the net difference in the expenditure on that product? Options
A) 12.5 %  B) 13 %  C) 13.15 %  D) 14 %  E) 15 %

Rationale: "quantity x rate = price 1 x 1 = 1 0.7 x 1.25 = 0.875 decrease in price = ( 0.125 / 1 ) × 100 = 12.5 % a )"
Answer: A