For a damped oscillator with m=0.50kg, k=200Nm−1 and b=2.0kgs−1, the natural angular frequency is ω0=20rads−1 and the resonance frequency is ωres=19.8rads−1. The percentage decrease in frequency due to damping is approximately
a) 2%
b) 1%
c) 0.5%
d) 4%