Task: Question Answering
Input (English): Problem: an ore contains 25 % of an alloy that has 90 % iron . other than this , in the remaining 75 % of the ore , there is no iron . how many kilograms of the ore are needed to obtain 60 kg of pure iron ? 
Options: a ) 250 kg , b ) 275 kg , c ) 300 kg , d ) 266.66 kg , e ) none
Output (English): d