Answer:
C ) 33 s.
Step-by-step explanation:
In simple harmonic motion damping of amplitude is logarithmic which is expressed as follows

A/A₀ = .3 (given ) , b is damping constant and t is time which is 30 s here.

ln .3 = -b / 30
1.2 = b / 30
b = 36 s 0r 33 s