Explanation: Solve: \[ V = \sqrt{1+4} = \sqrt{5} \] \[ B = \sqrt{4+9} = \sqrt{13} \] এখন, \[ \cos\theta = \frac{\vec{V}.\vec{B}}{VB} = \frac{0+4+0}{\sqrt{5}\sqrt{13}} \implies \theta = 60.25^\circ \] \[ F = qVB\sin\theta \implies F = 2 \cdot \sqrt{5} \cdot \sqrt{13} \cdot \sin(60.25^\circ) = 13.99 \approx 14 \, \text{N} \] Ans. (B)