Subject: mathqa
Question: during a sale , the price of a pair of shoes is marked down 10 % from the regular price . after the sale ends , the price goes back to the original price . what is the percent of increase to the nearest percent from the sale price back to the regular price for the shoes ?
Option: 
A: 10 %
B: 90 %
C: 9 %
D: 11 %
Answer: D