A particle moves along the \(x\)-axis with an instantaneous velocity given by the function \(v_x(t) = 3t^2 - 12t\), where \(v_x\) is in meters per second and \(t\) is in seconds. The particle's motion is observed over the time interval from \(t = 0\text{ s}\) to \(t = 5\text{ s}\). Which of the following correctly identifies the direction of the particle's average velocity vector and the relationship between its average speed \(s_{\text{avg}}\) and the magnitude of its average velocity \(|\vec{v}_{\text{avg}}|\) over this interval?