A cell 'A' with D.P.D. = 8 is surrounded by three cells 'B', 'C' and 'D' with D.P.D. respectively 4, 6 and 5. What shall be the direction of water movement?

1. $B\to A\leftarrow C$
$$ $$ $$ $$ $$ $$ $$ $\uparrow$
$$ $$ $$ $$ $$ $$ $$ $D$
2. A → B → C → D
3. D → C → B ← A
4. A → B ← C → D