19 甲、乙、丙 3 個細胞相鄰,甲細胞的 Ψs = – 0.7 MPa、Ψp = 0.4 MPa,乙細胞的 Ψs = – 0.8 MPa、Ψp = 0.4 MPa,丙細胞的 Ψs = – 0.7 MPa、Ψp = 0.5 MPa,有關細胞間水的流動方向,下列何者最適 當? (A)甲→乙→丙 (B)丙→乙→甲 (C)乙→甲→丙 (D)丙→甲→乙