Electromagnetism - RLC Circuit

In the RLC circuit shown, the applied voltage is ε(t) = ε_m cos ωt For a constant ε_m, at what angular frequency ω does the current have its maximum steady-state amplitude after the transients have died out?

A. 1/RC
B. 2L/R
C. 1/√(LC)
D. √[(1/LC) − (R/2L)²]
E.  √[(1/RC)² − (L/R)²]

(GR9277 #81)

Solution:

I_max when X_L = X_C

→ ωL = 1 / ωC

ω = 1/√(LC)

Answer: C