Task: Question Answering
Input (English): Problem: machine a produces 100 parts twice as fast as machine b does . machine b produces 100 parts in 40 minutes . if each machine produces parts at a constant rate , how many parts does machine a produce in 10 minutes ? 
Options: a ) 20 , b ) 50 , c ) 60 , d ) 40 , e ) 30
Output (English): b