discrete maths closed

Question

 P: Good mobile phones are not cheap
  Q: Cheap mobile phones are not good

  L: P implies Q
  M: Q implies P
  N: P is equivalent to Q 

Which one of the following about L, M, and N is CORRECT?

(A) Only L is TRUE.
(B) Only M is TRUE.
(C) Only N is TRUE.
(D) L, M and N are TRUE