Question

Annual NPP of land area on the earth is ______

• A. < 55 billion tons
• B. between 55 to 100 billion tons
• C. About 115 billion tons
• D. 225 billion tons

Hint:

Land NPP = total biosphere NPP minus ocean NPP.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The passage gives the net primary productivity of the whole biosphere and of the oceans. We need the share of land.

Step 2: Read the numbers:
The whole biosphere has about 170 billion tons a year. The oceans give about 55 billion tons of that.

Step 3: Calculate:
Land NPP is the total minus the ocean part.\[170 - 55 = 115\text{ billion tons}\]

Step 4: Check option 1:
Less than 55 billion tons would make land smaller than the ocean. Wrong.

Step 5: Check option 2:
55 to 100 billion tons is below 115. Wrong.

Step 6: Check option 3:
About 115 billion tons matches the subtraction. Correct.

Step 7: Check option 4:
225 billion tons is more than the whole biosphere total. Impossible. Wrong.

Final Answer:
\[\boxed{3}\]