Running at the same constant rate, 6 identical machines can produce a total of 240 bottles per minute. At this rate, how many bottles could 10 such machines produce in 4 minutes? Choose the correct choice from the following choices:
A) 648
B) 1,800
C) 1,600
D) 10,800
E) 64,800

Rationale: "6 machines produce 240 bottles per minute ; 1 machine produces 240 / 6 = 40 bottles per minute ; 10 machines produce 40 * 10 = 400 bottles per minute ; in 4 minutes 10 machines produce 400 * 4 = 1,600 bottles . answer : c ."
Answer: C