A block of mass \(m\) on a horizontal frictionless surface is connected to an ideal spring of spring constant \(k\). The entire apparatus is immersed in a viscous fluid that exerts a resistive drag force \(\vec{F}_d = -b\vec{v}\), where the damping constant satisfies \(b > 2\sqrt{mk}\). The block is displaced to position \(x = +x_0\) and released from rest at time \(t = 0\). Which of the following best describes the qualitative graph of the block's position \(x\) as a function of time \(t\)?