Question

healthy oceans and forests
a.
are a carbon dioxide source

b.
are a carbon dioxide sink

c.
are an example of positive feedback

d.
contribute most of the greenhouse gases

Explanation:

• Option A: Oceans and forests absorb CO₂, not release it as a source.
• Option B: Healthy oceans (via processes like photosynthesis in phytoplankton and carbon dissolution) and forests (via photosynthesis in trees) absorb carbon dioxide, acting as sinks.
• Option C: They relate to carbon sequestration, not positive feedback (which amplifies changes, e.g., melting ice reducing albedo).
• Option D: Human activities (e.g., burning fossil fuels) contribute most greenhouse gases, not oceans/forests.

Answer:

B. are a carbon dioxide sink