Explanation
(a) Mining projects — Correct
• Mining causes large-scale land disturbance, habitat loss, groundwater depletion, and pollution.
• As per EIA Notification, 2006, mining (including coal, sand, and major minerals) requires prior environmental clearance.
(b) Thermal power plants — Correct
• Thermal plants emit pollutants (SO₂, NOx, particulates) and large carbon emissions.
• All coal-based and gas-based thermal power plants fall under the mandatory EIA category.
(c) River valley projects — Correct
• Dams, hydroelectric power stations, and irrigation barrages significantly impact river flow, sediment load, biodiversity, and displacement of people.
• These projects also require public hearings and EIA approval.
Therefore, all three categories require mandatory Environmental Impact Assessment.