At any place on earth, the horizontal component of earth's magnetic field is  times the vertical component. The angle of dip at that place will be-

$60^o$ $45^o$ $90^o$ $30^o$

$30^o$

$tan \theta = \frac{B_V}{B_H} = \frac{B_V}{\sqrt 3 B_V} = \frac{1}{\sqrt 3}$ $ \theta = 30^o$