Two point charges $q_{1}=2 \mu c$ and $q_{2}=1 \mu c$ are placed at distance $\mathrm{b}=1 \mathrm{~cm}$ and $\mathrm{a}=2 \mathrm{~cm}$ from the origin on the $\mathrm{y}$ and $\mathrm{x}$ axes as shown in figure. The electric field vector at point $\mathrm{P}(\mathrm{a}, \mathrm{b})$ will subtend an angle $\theta$ with the $\mathrm{X}$ - axis given by,
(A) $\tan \theta=4$
(B) $\tan \theta=1$
(C) $\tan \theta=3$
(D) $\tan \theta=2$