Question

carbon molecules make up about 18 percent of which of these? choose one option a complex carbohydrates b human body mass c omega-3 fatty acids d earth’s crust

Explanation:

To solve this, we analyze each option:

• Option A: Complex carbohydrates have a higher carbon percentage (e.g., formula like \((C_6H_{10}O_5)_n\) has more C relative to H and O, way more than 18%).
• Option B: The human body mass is composed of elements, and carbon makes up about 18% of it (other major elements: O ~65%, H ~10%, N ~3% etc.).
• Option C: Omega - 3 fatty acids are lipids, with a high proportion of C and H, carbon percentage is much higher than 18%.
• Option D: Earth’s crust has very little carbon (less than 1%), mainly composed of O, Si, Al, Fe etc.

Answer:

B. Human body mass