If a (ast) b = + (sqrt{ab}), evaluate 2 (ast)(12 (ast) 27)

A.
12 
B.
9 
C.
6 
D.
2
Correct Answer: Option C
Explanation
(2 ast (12 ast 27))
(12 ast 27 = + sqrt{12 times 27})
= (+ sqrt{324} = 18)
(2 ast 18 = + sqrt{2 times 18})
= (+ sqrt{36} = 6)