J and N cannot both be on.
If M is off, either J or N is on; if either J or N is on, M is off.
If P is on, L is on.
If O is off, N is off; if O is on, N is on.
Assume that the circuit is working as designed.
18. Any of the following can be true EXCEPT:
(A) J and O are both off.
(B) K and N are both off.
(C) K and P are both on.
(D) L and M are both on.
(E) N and O are both on.
19. If L and O are on, which one of the following must be true?
(A) J is and K is off.
(B) J is off and N is on.
(C) K is off and M is on.
(D) K is off and P is on.
(E) M is off and P is on.
20. Which one of the following can be true?
(A) Only J, K, and M are off.
(B) Only J, L, and M are off.
(C) Only K, M, and O are off.