As shown, three resistors are arranged in parallel across a power supply. The power dissipated in the resistors with resistances $2\,\Omega$, $3\,\Omega$ and $4\,\Omega$ is $P_2$, $P_3$ and $P_4$ respectively. What is the ratio $P_2 : P_3 : P_4$?
- A$2 : 3 : 4$
- B$4 : 3 : 2$
- C$6 : 4 : 3$
- D$36 : 16 : 9$