In a rectangle ABCD, AB = 2l and BC = l. The centre of rectangle is at the origin of co-ordinate system. AB and CD are parallel to X-axis. The M.I. is least about 

The distribution is such that the more mass is farther from the axis, and the moment of inertia is least near an axis that passes through COM. The distance between yy' and BC is l if we take yy', whereas xx"s distance to AB is l/2. Therefore, because greater mass is distributed closer to xx' than yy', its moment of inertia is at its lowest point at xx'.

Hence the correct answer is x-axis.