Option A: 30°
Here, height of tree = 10 m, horizontal distance = $10\sqrt{3}$ m. $\tan\theta = \frac{10}{10\sqrt{3}} = \frac{1}{\sqrt{3}}$, so $\theta = 30°$.
Use $\tan(\text{angle of depression}) = \frac{\text{height}}{\text{horizontal distance}}$. Since the peacock looks down, the angle of depression equals the angle whose tangent is $\frac{10}{10\sqrt{3}} = \frac{1}{\sqrt{3}}$, giving 30°. A common mistake is inverting the ratio and getting 60°—always put height in the numerator and base distance in the denominator when using tan for angle of depression from the top.