In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be the potential sites for carbon sequestration ? 1. Abandoned and uneconomic coal seams 2. Depleted oil and gas reservoirs 3. Subterranean deep saline formations Select the correct answer using the code given below :

Defines carbon capture and storage (CCS) as capturing CO2 and permanently storing it underground, establishing that underground storage is an accepted mitigation approach.

A student can combine this with facts about coal seams being underground reservoirs to ask whether specific seam geology could serve as CCS sites.

Describes coal seams as enormous, thick and geographically distributed underground deposits (Damuda series), indicating the physical existence of substantial underground coal strata.

One could use a geological map to locate thick/abandoned seams and then evaluate their depth, extent and structural setting for potential CO2 storage.

Notes that fossil fuels were buried and can remain buried for millions of years until geological movements expose them—showing that buried carbon reservoirs can be long-term underground stores.

A student might infer that if buried carbon can remain sequestered naturally, engineered injection into stable buried formations (like seams) could likewise be long-term, subject to geological stability checks.

Gives an example of tertiary coal deposits (e.g., Neyveli lignite) with seam thickness (10–12 m), showing that some seams are sufficiently thick to consider as discrete underground units.

Using seam thickness and location data, a student could estimate storage volume potential and assess whether abandoned seams might hold meaningful CO2 volumes.

Describes physical characteristics of bituminous/coking coal occurring in compressed seams, implying varied seam properties (density, compression) that could affect fluid flow and storage behavior.

A student could extend this by checking whether seam permeability and compaction (not given here) would permit CO2 injection and retention in specific coal types.