The height of a tower is h meters. It is found that, when walking 100 m towards it in a horizontal line through its base, the elevation of its top changes from 30° to 60°, h is equal to:

Correct option is D

Given:

Initial angle = 30°
Final angle = 60°
Distance walked = 100 m

Formula:
tan(θ) = height / base

Solution:
Let final distance from tower = x
Then from triangle with 60°:
tan(60°) = h / x → √3 = h / x → h = x√3

From triangle with 30°:
tan(30°) = h / (x + 100) → 1/√3 = h / (x + 100)

Substitute h from above:
1/√3 = (x√3) / (x + 100)
Cross-multiplying:
x + 100 = 3x → 2x = 100 → x = 50
Then h = x√3 = 50√3

Final Answer: (d) 50√3 m