Task: Question Answering
Input (English): Problem: running at the same constant rate , 6 identical machines can produce a total of 420 bottles per minute . at this rate , how many bottles could 10 such machines produce in 4 minutes ? 
Options: a ) 648 , b ) 1800 , c ) 2800 , d ) 10800 , e ) 10900
Output (English): c