a) $$50\sqrt 3 $$
b) $$50$$
c) $$\frac{{50}}{{\sqrt 2 }}$$
d) $$\frac{{50}}{{\sqrt 3 }}$$

Answer: b
Explanation: Let AB be tower and C is a point on the ground 50 m away

From foot of tower B
Angle of elevation is 45°
Let h be height of tower = x m
$$\eqalign{ & \tan \theta = \frac{{AB}}{{BC}} \cr & \tan {45^ \circ } = \frac{{AB}}{50} \cr & 1 = \frac{{AB}}{{50}} \Rightarrow AB = 50\,m \cr} $$