Correct option is B
Let the ∠2, ∠3 and ∠4 be x
Sum of angles on a straight line = ∠5 + ∠4
150° + x = 180°
x = 30°
Sum of angles on a straight line = ∠1 + ∠2 + ∠3
∠1 + x + x = 180°
∠1 + 2x = 180°
∠1 + 2 × 30° = 180°
∠1 + 60° = 180°
∠1 = 120°

