Detailed Explanation:

Answer: Option 3 — All three

All three activities mentioned are recognized methods for carbon capture and sequestration (CCS) that are actively discussed in climate mitigation strategies.

✅ Activity 1 – Correct: Spreading finely ground basalt rock on farmlands (enhanced weathering) captures atmospheric CO₂ through chemical weathering reactions that form stable carbonates, effectively sequestering carbon in the soil.

✅ Activity 2 – Correct: Increasing ocean alkalinity by adding lime enhances the ocean's natural capacity to absorb and store atmospheric CO₂ by shifting the carbonate equilibrium, making oceans a more effective carbon sink.

✅ Activity 3 – Correct: Capturing industrial CO₂ emissions and storing them as carbonated water in abandoned subterranean mines is a direct carbon capture and storage (CCS) technique that prevents greenhouse gases from entering the atmosphere.

📝 Short Notes: Carbon Capture and Sequestration Methods

• Enhanced Weathering: Accelerates natural rock weathering by spreading silicate minerals (like basalt) on land; reacts with CO₂ to form stable carbonates that lock carbon for thousands of years.
• Ocean Alkalinization: Adding alkaline substances (lime, olivine) to oceans increases pH and carbonate concentration, enhancing CO₂ absorption capacity and counteracting ocean acidification.
• Geological Sequestration: Industrial CO₂ is captured at source, compressed, and injected into deep geological formations (depleted oil/gas fields, saline aquifers, mines) where it mineralizes or remains trapped.
• Other CCS Methods: Afforestation, soil carbon sequestration, biochar application, direct air capture (DAC), and bioenergy with carbon capture and storage (BECCS).
• Global Significance: CCS technologies are essential for achieving net-zero emissions targets and limiting global warming to 1.5-2°C as outlined in the Paris Agreement.