$\overrightarrow{ B }=\frac{\mu_0}{4 \pi} q \frac{\overrightarrow{ v } \times \overrightarrow{ r }}{ r ^3}$ and $\overrightarrow{ E }=\frac{1}{4 \pi \epsilon_0} \frac{ q \overrightarrow{ r }}{ r ^3}$
$\mu_0 \in_0(\overrightarrow{ v } \times \overrightarrow{ E })=\frac{\overrightarrow{ v } \times \overrightarrow{ E }}{ c ^2}=\frac{(\hat{ i }+3 \hat{ j }) \times 2 \hat{ k }}{ c ^2}$
$=\frac{-2 \hat{ j }+6 \hat{ i }}{ c ^2}=\frac{6 \hat{ i }-2 \hat{ j }}{ c ^2}$
$\left[c=\frac{1}{\sqrt{\mu_0 \epsilon_0}} \Rightarrow \mu_0 \in_0=\frac{1}{c^2}\right]$


$(A)$ If $\vec{B}$ is along $\hat{z}, F \propto(L+R)$
$(B)$ If $\overrightarrow{ B }$ is along $\hat{ x }, F =0$
$(C)$ If $\vec{B}$ is along $\hat{y}, F \propto(L+R)$
$(D)$ If $\overrightarrow{ B }$ is along $\hat{ z }, F =0$
(mass of proton $=1.67 \times 10^{-27} \,kg ,$ charge of the proton $\left.=1.6 \times 10^{-19}\, C \right)$