If the operation € is defined for all x and y by the equation x € y = 2*x*y, then 9 € (4 € 5) =	Choose the correct choice from the following:
A) 80 B) 720 C) 760 D) 840 E) 860

Rationale: "working inside out , ( 4 € 5 ) = 2 * 4 * 5 = 40 9 € 40 = 2 * 9 * 40 = 720 hence , answer is b"
Answer: B