# Velocity and acceleration vectors of charged particle moving perpendicular to the direction of a magnetic field at a given instant of time are $\overrightarrow v=2 \hat i+c \hat j$ and $\overrightarrow a=3 \hat i+4 \hat j$ respectively. Then the value of c is

$\begin {array} {1 1} (a)\;3 & \quad (b)\;1.5 \\ (c)\;-1.5 & \quad (d)\;-3 \end {array}$

(c) -1.5