Consider the following activities: 1. Spreading finely ground basalt rock on farmlands extensively 2. Increasing the alkalinity of oceans by adding lime 3. Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters. How many of the above activities are often considered and discussed for carbon capture and sequestration?

1. Spreading finely ground basalt rock on farmlands extensively — This is discussed as enhanced rock weathering; basalt reacts with CO2 and helps lock carbon in bicarbonates/carbonates. Verdict: Correct.

2. Increasing the alkalinity of oceans by adding lime — This is a known ocean alkalinity enhancement proposal to increase oceanic CO2 uptake. Verdict: Correct.

3. Capturing carbon dioxide released by industries and pumping it into abandoned subterranean mines in the form of carbonated waters — CO2 mineralization/storage in subsurface formations via dissolved or carbonated water is also discussed under carbon capture and sequestration approaches. Verdict: Correct.

Hence, all three are considered/discussed for carbon capture and sequestration.