The molal depression constant for water is $1.86 \, ^\circ C \, kg \, mol^{-1}$. The freezing point of a $0.05 \, m$ solution of a non-electrolyte in water is:

• A
  $-1.86 \, ^\circ C$
• B
  $-0.93 \, ^\circ C$
• C
  $-0.093 \, ^\circ C$
• D
  $0.93 \, ^\circ C$