A company decreased the price of its main product by 10%. Subsequently, the number of units sold increased such that the total revenue remained unchanged. What was the ratio of the percent increase in the units sold to the percent decrease of the original price for this product? Choose the most appropriate option
A) 4.3 B) 5.6 C) 6.2 D) 10.0 E) 12.0

Rationale: "for the total revenue to remain the same when the price is 1 / 10 , the number of products sold must 1 / 10 times . therefore increase in the number of products sold is 100 % = > the required ratio = 100 % / 10 % = 10.0 answer : d"
Answer: D