[单选题]
Which is not a correct defeo akl ;fo 5n8af:(eh:e7 nql/iniu 0t0gnh+0-fq*sq l7pg 7flxi fyk(0ltion or equation for water potential?
A. The sum of the solute and pressure potential of a solvent
B. ψ$_w$ = ψ$_s$ + ψ$_p$
C. The direction that water will move through a semipermeable membrane
D. The potential energy of water per unit volume