A non-uniform thin rod of mass \(M\) and length \(L\) is pivoted about a fixed horizontal axis through one end at \(x = 0\), allowing it to oscillate freely in a vertical plane as a physical pendulum. The linear mass density of the rod as a function of distance \(x\) from the pivot is given by \(\lambda(x) = Cx\), where \(C\) is a constant. Which of the following expressions represents the period \(T\) of small oscillations of the rod?