Consider the following activities: How many of the above activities are often considered and discussed for carbon capture and sequestration?

Answer: (c) All three

All three are discussed ways to capture and store carbon.

Statement by statement

1. ✓ YES Enhanced rock weathering: crushed basalt reacts with CO₂ and can form stable carbonates.

2. ✓ YES Ocean alkalinity enhancement: adding lime lets seawater absorb more CO₂.

3. ✓ YES Injecting captured CO₂ as carbonated water underground mineralises it in rock (e.g. Iceland’s CarbFix).

The idea

Nature already removes carbon dioxide from the air, very slowly: rain water with dissolved CO₂ reacts with rock and the carbon ends up locked in minerals and in the sea. This is weathering. All three activities in the question copy this natural process and try to speed it up.

Crushed basalt on fields → more rock surface → reacts with CO₂ faster → Lime in the ocean → sea water becomes more alkaline → holds more CO₂ → CO₂ dissolved in water and pumped into rock → turns into carbonate minerals

The trap

Spreading rock on farms sounds like fertiliser, not climate action.

Also know

The third method is used in Iceland, where dissolved CO₂ injected into basalt turns to stone within about two years. India’s Deccan Traps are a very large basalt area and are studied for the same purpose. Other removal methods: planting forests, biochar, bioenergy with carbon capture, and direct air capture.