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:
Find land NPP using the passage totals.

Step 2: Use a share method:
Oceans are \(\frac{55}{170}\approx 32\%\) of the total. So land is about \(68\%\).

Step 3: Convert:
\(0.68\times 170\approx 115\) billion tons.

Step 4: Rule out big values:
Land cannot exceed 170, so 225 is out.

Step 5: Rule out small values:
Land is the larger part, about two thirds, so values under 100 are out.

Step 6: Match:
Option 3 fits.

Quick Recap:
Recap: both the subtraction method and the percentage method give the same value of 115 billion tons, which gives confidence in option 3. The other values are either below the ocean figure, below the land share, or above the total.

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