Task: Question Answering
Input (English): Problem: the average salary per head of the entire staff of an office including the officers and clerks is rs . 90 . the average salary of officers is rs . 600 and that of the clerks is rs . 84 . if the number of officers is 2 , find the number of officers in the office ? 
Options: a ) 1 , b ) 8 , c ) 7 , d ) 6 , e ) 2
Output (English): a