Question 1063430
I think the answer is {{{highlight(C.  36)}}}.  Here's the logic:

A.  12  =  12 / 2 * 2  (even number of operations, so in 60 operations we can also reach 12)
B.   18  = 12 / 2 * 3    (even)
C.   36  = 12 /2 * 3 * 2  (it takes an odd number of operations to go from 12 to 36)
D.  72 =  12 * 2 * 3       (even)
E.   108 = 12 * 3 * 3     (even)