Task: Question Answering
Input (English): Problem: you have a flashlight that takes 2 working batteries . you have 8 batteries but only 4 of them work . what is the fewest number of pairs you need to test to guarantee you can get the flashlight on ? 
Options: a ) 5 , b ) 8 , c ) 7 , d ) 6 , e ) 4
Output (English): c