Which of the following will have the lowest total vapor pressure at \(25^{\circ} \mathrm{C}\) ?

a. pure water

b. a solution of glucose in water with \(\chi_{\text {glucose }}=0.01\)

c. a solution of sodium chloride in water with \(\chi_{\mathrm{NaCl}}=0.01\)

d. a solution of methanol in water with \(\chi_{\mathrm{CH}_{3} \mathrm{OH}}=0.2\)

(At \(25^{\circ} \mathrm{C}\), the vapor pressure of pure methanol is 143 torr.)