Answer:
(B) 60
Explanation:
From the figure, it is given that MNOP is a rectangle and ∠MON=60°.
Now, Since from the properties of rectangle, the diagonals are congruent and bisect each other, therefore ∠PNO=60°.
Now, using the angle sum property in ΔNDO, we have

Substituting the given values, we get
⇒

⇒

⇒

⇒

Now, since
( Vertically opposite angle)
Thus, the value of x is 60°
Hence, option B is correct.