Which of the following best defines the term 'Blue Carbon'?

The correct option is Carbon bound and sequestered by coastal and oceanic habitats such as mangrove forests.

Explanation:

"Blue Carbon" refers to the carbon dioxide captured and stored from the atmosphere and oceans by marine and coastal ecosystems. Key blue carbon ecosystems include mangrove forests, seagrass meadows, and tidal marshes.
These coastal habitats are exceptionally efficient at absorbing carbon dioxide through photosynthesis and storing it in their biomass as well as deep within the organic-rich sediments beneath them for hundreds to thousands of years.

Let's evaluate the given choices:
1. Carbon trapped deep inside polar permafrost layers: Permafrost stores terrestrial organic carbon, but it is not classified under blue carbon.
2. Carbon captured using advanced industrial filtration devices: This describes technological carbon capture and storage (CCS) or direct air capture (DAC), not natural biological sequestration.
3. Carbon pollution released by maritime container ships: This refers to anthropogenic greenhouse gas emissions from marine transport.
4. Carbon bound and sequestered by coastal and oceanic habitats such as mangrove forests: This accurately defines the ecological concept of blue carbon.