The centre of mass of a non-uniform rod of length \[L\] whose mass per unit length \[\lambda \] varies as \[\lambda =\frac{k.{{x}^{2}}}{L}\]where k is a constant and x is the distance of any point on rod from its one end, is (from the same end)

• A. \[\frac{3}{4}L\]
• B. \[\frac{1}{4}L\]
• C. \[\frac{k}{L}\]             
• D. \[\frac{3k}{L}\]