Correct Answer - Option 2 : y alone
1) P is equal to or not shorter than Q.
⇒ P ≥ Q
2) N is as tall as P.
⇒ N = P ≥ Q
3) M is taller than or equal to N.
⇒ M ≥ N = P ≥ Q
Conclusions:
(x) M is taller than P → False (M ≥ N = P → M ≥ P)
(y) N is equal to or taller than Q → True (N = P ≥ Q → N ≥ Q)
Hence, option 2 is the correct answer.