In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a company produces on an average 4000 items per month for the first 3 months . how many items it must produce on an average per month over the next 9 months , to average of 4375 items per month over the whole ? 
Options: a ) 4500 , b ) 4600 , c ) 4680 , d ) 4710 , e ) none
a

Problem: 19.19 / 2000 is equal to : 
Options: a ) 1.01252633 , b ) 0.01262533 , c ) 0.12526333 , d ) 0.012793333 , e ) 0.12725333
d

Problem: a number is increased by 70 % and then decreased by 70 % . find the net increase or decrease per cent . 
Options: a ) 49 % , b ) 18 % , c ) 17 % , d ) 13 % , e ) 16 %

a