For an ideal solution containing a nonvolatile solute, which of the following expression represents the vapour pressure of the solute ? `(x_(1)rarr` mole fraction of solvent)
A. `p = x_(2) p_(2)`
B. `p = x_(1)p_(2)`
C. `p = x_(1)p_(1)`
D. `p_(1) - p = x_(2)`
