a) 30°
b) 60°
c) 45°
d) None of these

Answer: c
Explanation:

Consider the diagram shown above where QR represents the tree and PQ represents its shadow
$$\eqalign{ & {\text{We}}\,{\text{have}},\,QR = PQ \cr & {\text{Let}}\,\angle QPR = \theta \cr} $$
$$\tan \theta = \frac{{QR}}{{PQ}} = 1$$     (since QR = PQ)
$$ \theta = {45^ \circ }$$
i.e., required angle of elevation = 45°