\\\\(m=\\\\) mass of rectangular magnet \\\\(M=\\\\) Magnetic moment Moment of inertia, \\\\(I_1\\propto l^2 m\\\\)Time period, T \\\\(\\propto \\dfrac{\\sqrt I}{\\sqrt M}\\\\)Therefore, time period \\\\(T\\propto l \ imes \\sqrt{\\dfrac{m}{M}}\\\\)when magnet is cut then mass and magnetic moment becomes half.Hence, time period becomes halfOption B is answer.