a, b, c, and d are positive integers where a is a factor of b and c is a factor of d. Which of the following is NOT necessarily an integer?	Choose the correct choice from the following answers:
A) (ac)/(bd)
B) (bd)/(ac)
C) (bcd)/a
D) d/c + b/a
E) (a + b)d/c
As per the question, let a = 2, b = 6, c = 5, and d = 10. Plugging these into the answer choices, only (ac)/(bd) does not yield an integer.
<result>A</result>
a, b, c, and d are positive integers where a is a factor of b and c is a factor of d. Which of the following is NOT necessarily an integer?