John professes to sell his goods at the cost price but he made use of 800 grams instead of a kg, what is the gain percent? Choose the correct choice from the following:
A) 12 1/3%  B) 12 1/4%  C) 12 2/3%  D) 12 2/1%  E) 12 1/2%
800 --- 100   100 --- ? =&gt; 12 1/2%   Answer:12 1/2%
<result>E</result>
John professes to sell his goods at the cost price but he made use of 800 grams instead of a kg, what is the gain percent?