Irrigation

Correct answer: A. It delivers water directly to roots

The governing concept is efficient irrigation in a water-scarce environment. A drip system releases small, controlled quantities of water through emitters near the root zone. Water is supplied where the crop can use it, so less is lost through evaporation, wind drift, or runoff than in many forms of surface irrigation. This is especially valuable in arid regions, where rainfall is limited and evaporation is high. Option A is correct because direct delivery to roots improves water-use efficiency. Options B, C, and D are incorrect: a properly managed drip system reduces wastage, does not remove soil, and can reduce dependence on uncertain rainfall.

Correct answer: A. Waterlogging and salinity

The governing concept is the environmental impact of poorly managed irrigation. When more water is applied than the soil and crops can use, the water table may rise toward the surface. Air spaces in the soil become filled with water, producing waterlogging and reducing oxygen available to roots. In dry climates, evaporation can then leave dissolved salts behind at or near the surface, causing salinity and lowering soil productivity. Option A is correct because it names both linked problems. The other options are unrelated or exaggerated: irrigation does not expand forests, purify air, or completely eliminate soil erosion.