The plot of osmotic pressure ($\Pi$) vs concentration (mol L$^{-1}$) for a solution gives a straight line with slope 25.73 L bar $mol^{-1}$. The temperature at which the osmotic pressure measurement is done is: (Use $R = 0.083$ L bar $mol^{-1} K^{-1}$)
A $25.73^\circ C$
B $12.05^\circ C$
C $37^\circ C$
D $310^\circ C$