Question

what is the main reason why there are \pyramids\ of numbers, biomass and energy in ecosystem structure rather than \squares\,
ectangles\ or other geometric shapes? the reason is unknown. the 10% rule accounts for this geometric structure. this is due to over - harvesting by humans.

Explanation:

The 10% Rule (energy transfer efficiency) explains pyramid - shaped structures. Energy decreases at each trophic level (about 10% transfer), so numbers, biomass, and energy form pyramids. Over - harvesting isn't a general cause for all ecosystems. And the reason isn't unknown as ecological principles (like the 10% Rule) explain it.

Answer:

B. The 10% Rule accounts for this geometric structure.