# A mass M kg is suspended by a weightless string. The horizontal force that is required to displace it untill the string makes an angle $45^{\circ}$ with initial vertical direction is
$(a)\;Mg(\sqrt 2 +1)\quad (b)\;Mg \sqrt 2 \quad (c)\;\frac{mg}{\sqrt 2}\quad (d)\;Mg(\sqrt 2-1)$