Marc wants to make a minimum net profit of 20% on a his headphones, which he bought for $500. If originally, he was selling the pair at 25% gain, what is the largest discount he can allow?	Choose the correct option:
A) 10% B) 0% C) 5% D) 3% E) 4%
E   If he bought the headphones at $500, he is currently selling them at (115/100)*500 = $625.   He wants to make a profit of 20%, which means he needs to sell them at   (120/100)*500= 
<gadget id="calculator">  (120/100)*500</gadget>
<output>600</output>
$600   The max discount he can allow is thus   ((625-600)/625)*100= 
<gadget id="calculator">  ((625-600)/625)*100</gadget>
<output>4</output>
4%
<result>E</result>
Marc wants to make a minimum net profit of 20% on a his headphones, which he bought for $500. If originally, he was selling the pair at 25% gain, what is the largest discount he can allow?