A solution of urea (mol. mass $56\;g\;mol^{-1}$) boils at $100.18^{\circ}C$ at the atomospheric pressure. If $K_f$ and $K_b$ for water are $1.86$ and $0.512\;K g\;mol^{-1}$ respectively , the above solution will freeze at :-

Question

( A ) $0.654^{\circ}C$
( B ) $-6.54^{\circ}C$
( C ) $-0.654^{\circ}C$
( D ) $6.54^{\circ}C$