In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: running at the same constant rate , 6 identical machines can produce a total of 270 bottles per minute . at this rate , how many bottles could 8 such machines produce in 4 minutes ? 
Options: a ) 648 , b ) 1800 , c ) 2700 , d ) 1440 , e ) none of these
d

Problem: a merchant sells an item at a 20 % discount , but still makes a gross profit of 20 percent of the cost . what percent p of the cost would the gross profit on the item have been if it had been sold without the discount ? 
Options: a ) 20 % , b ) 40 % , c ) 50 % , d ) 60 % , e ) 75 %
c

Problem: a reduction of 30 % in the price of oil enables a house wife to obtain 9 kgs more for rs . 900 , what is the reduced price for kg ? 
Options: a ) 72 , b ) 27 , c ) 40 , d ) 30 , e ) 20

d