Distance from the building where the fireman is standing = 25 m due west
Angle of elevation of the ladder = 51 degrees
Then
Let us assume the length of the ladder = x
Then
Cos 51 degree = 25/x
0.6293 = 25/x
x = 25/0.6293
= 39.72 meters
= 40 meters
From the above deduction, we can conclude that the correct option among all the options given in the question is the fourth option or option "D".
