Which physical process primarily enables plant roots to absorb water from the soil?

Correct answer: Osmosis

Correct answer: B, osmosis. Water enters root-hair cells across selectively permeable membranes when the water potential of the surrounding soil solution is higher than that inside the cells. In simple terms, water moves toward the region with relatively more dissolved solute, provided the membrane allows water to pass. This movement is osmosis and is an important part of root water absorption. A is wrong because gravity mainly pulls water downward and does not create the basic entry of water into root cells. C is wrong because atmospheric pressure is not the primary cell-level mechanism. D is wrong because centrifugal force has no normal role in root absorption. Active transport of mineral ions can also help establish gradients, and transpiration can pull water upward later, but those ideas do not replace osmosis as the answer here. Memory cue: osmosis is water crossing a selective membrane toward lower water potential.