The following second-order homogeneous linear differential equations model the vibrations of a spring-mass system:                                                       Equation (1): 36 𝑥 ″ + 60 𝑥 ′ + 25 𝑥 = 0 Equation (2): 49 𝑥 ″ + 4 𝑥 = 0 Equation (3): 18 𝑥 ″ + 21 𝑥 ′ + 5 𝑥 = 0 Equation (4): 49 𝑥 ″ + 14 𝑥 ′ + 5 𝑥 = 0 The motion of the spring-mass system modeled by Equation (1) is classified as [ Select ] Underdamped motion Free undamped motion Critically damped motion Overdamped motion . The motion of the spring-mass system modeled by Equation (2) is classified as [ Select ] Underdamped motion Overdamped motion Critically damped motion Free undamped motion . The motion of the spring-mass system modeled by Equation (3) is classified as [ Select ] Underdamped motion Critically damped motion Overdamped motion Free undamped motion . The motion of the spring-mass system modeled by Equation (4) is classified as [ Select ] Overdamped motion Underdamped motion Critically damped motion Free undamped motion .