In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be potential sites for carbon sequestration?

1. Abandoned and uneconomic coal seams — CO2 can be injected into unmineable coal seams and gets adsorbed onto coal surfaces; this is a recognized carbon sequestration option. Verdict: Correct.

2. Depleted oil and gas reservoirs — These reservoirs have already trapped hydrocarbons for geological timescales and are standard candidates for CO2 storage, including in enhanced oil recovery contexts. Verdict: Correct.

3. Subterranean deep saline formations — Deep saline aquifers are among the largest and most widely accepted geological storage sites for CO2 sequestration. Verdict: Correct.

Since 1, 2 and 3 are all potential sites for carbon sequestration, the correct answer is (d).