Damping of a Spring System

Classical Mechanics

A $2 \text{kg}$ mass attached to a spring of spring constant $k = 10 \text{ N}/\text{m}$ oscillates through a fluid that exerts a damping force $F_d = -(4 \text{ N}\cdot\text{s}/\text{m})\: v$ on the mass, where $v$ is the velocity of the mass. Which of the following correctly describes the oscillatory behavior of the system?