For every even positive integer m, f(m) represents the product of all even integers from 2 to m, inclusive. For example, f(12)=2x4x6x8x10x12. What is the greatest prime factor of f(28)? Choose the correct option.
A) 2	B) 7	C) 11	D) 13	E) 17
f(28) = 2*4*6*8*10*12*14*16*18*20*22*24*26*28   The greatest prime factor in this list is 13.   The answer is 13.
<result>D</result>
For every even positive integer m, f(m) represents the product of all even integers from 2 to m, inclusive. For example, f(12)=2x4x6x8x10x12. What is the greatest prime factor of f(28)?