How Long Will It Take a Charged 80- $\mu$ F Capacitor to Lose 20% of Its Initial Energy When

Multiple Choice

How long will it take a charged 80- $\mu$ F capacitor to lose 20% of its initial energy when it is allowed to discharge through a 45- $\Omega$ resistor?

A) 0.92 ms
B) 0.64 ms
C) 0.40 ms
D) 0.19 ms
E) 0.80 ms