A thin, non-uniform rod of length \(L\) and total mass \(M\) is placed along the \(x\)-axis with one end at the origin. The linear mass density of the rod varies with position according to the function \(\lambda(x) = cx^2\), where \(c\) is a constant. Which of the following expressions represents the rotational inertia of the rod about an axis through the origin and perpendicular to the rod, in terms of \(M\) and \(L\)?