The point of observation is 2500 m away from the foot of the building.
The angle of elevation is 4°.
We need to find the height 'h' of the building.
With respect to 4°,
2500 is the adjacent side.
'h' is the opposite side.
The trigonometric ratio associating opposite & adjacent is tan.
We have
[tex] tan\theta =\frac{opposite}{adjacent} [/tex]
[tex] tan4^{o}=\frac{h}{2500} [/tex]
Cross multiplying we get
h = 2500 tan4°
h= 174.82 m
Option B) is the right answer.