Why is the nature of the river bed important in groundwater recharge by rivers?

Correct answer: A permeable bed lets water move downward

Direct answer: A, a permeable river bed lets water move downward. Groundwater recharge means surface water enters the soil and replenishes underground water. The step-by-step chain is: river water touches the bed; if the bed has pores, sand, gravel, cracks, or other openings, water can seep through; gravity carries some of that water downward; it may then add to the groundwater store. A permeable bed therefore supports recharge, although recharge also depends on water availability, time, soil, and geology. Option A is correct because it states this direct surface-water-to-groundwater connection. Option B is wrong because an impermeable bed blocks or greatly reduces downward seepage; it does not always give more recharge. Option C is wrong because the river bed is the contact surface through which seepage can occur, so it clearly has a relation to groundwater. Option D is wrong because river beds are formed by erosion, deposition, rocks, sediment, and flowing water, not only by sunlight. Exam cue: “permeable means passage”; water can pass through it.