A small particle of mass \(m\) travels in the \(xy\)-plane with a constant velocity \(\vec{v} = v_0\,\hat{i}\) along the straight line \(y = b\), where \(b > 0\). The particle moves from \(x = -d\) to \(x = +d\), where \(d > b\). Which of the following correctly describes the magnitude of the particle's angular momentum about the origin during this motion, and provides the correct justification?