Convert the given complex number in polar form :$\;1-i\;$

Question

$(a)\;0\qquad(b)\;\sqrt{2}\;[cos (-\pi)+i \;sin(- \pi)]\qquad(c)\;\sqrt{2}\;[cos (-\large\frac{\pi}{2})+i \;sin(-\large\frac{\pi}{2})]\qquad(d)\;\sqrt{2}\;[cos (-\large\frac{\pi}{4})+i \;sin(-\large\frac{\pi}{4})]$