7. A series RLC circuit, driven with a sinusoidal external emf with rms voltage 120 V, contains a resistance R = 200 Ω, an inductance L =1.0 H , and a capacitance C = 16 μF. What is the resonance frequency of this circuit? (A) 960 Hz (B) 1,600 Hz (C) 40 Hz (D) 6,400 Hz (E) 250 Hz