A Spring with a Mass Of $9 \mathrm {~kg}$ Has Damping Constant 28 and Spring Constant 195

Multiple Choice

A spring with a mass of $9 \mathrm {~kg}$ has damping constant 28 and spring constant 195 . Find the damping constant that would produce critical damping. Select the correct answer.

A) $c = 36 \sqrt { 195 }$
B) $c = 2340$
C) $c = 195 \sqrt { 9 }$
D) $c = 9 \sqrt { 195 }$