Exercise $4$: Particle A has the same speed as particle $B$ and four times the kinetic energy of particle $B.$ What is the ratio of their masses $\frac{m_A}{m_B}$ :

$($a$)4$

$($b$)2$

$($c$)1$

$($d$)\frac{1}{2}$

$($e$)\frac{1}{4}$