Answer:
The correct answer is : approximately 3 gT yr^-1 decrease
Step-by-step explanation:
Carbon dioxide is contribute and removed from the atmosphere by various type of activities that are human activities, biological input or biological removal and geological input or geological removal.
Adding carbon dioxide can be from biological inputs mainly respiration and removed from atmosphere mainly through biological removal mainly photosynthesis.
Both photosynthesis are complementary metabolic process that play major role of adding and removal of carbon dioxide. There is a decrease of 3gT yr^-1 approximately on the annual basis due to these biological process.