Question

ecological pyramids are a good model to use to show the relationships between trophic levels in an ecosystem because
a they are exact
b it shows that the lower levels are needed to support the higher levels
c it shows that the higher levels are bigger than the lower levels
d it shows that the higher levels do not need any support from the lower levels

Explanation:

Ecological pyramids illustrate the energy, biomass, or number of organisms at each trophic level. Lower trophic levels (like producers) provide energy and resources that support higher trophic levels (like consumers). Option A is incorrect as they are not "exact" in all cases (e.g., inverted pyramids can exist for biomass in some aquatic ecosystems). Option C is wrong because usually lower - level biomass or numbers can be larger (e.g., in a grassland, there are many grass plants (producers) compared to a few top - level carnivores). Option D is incorrect as higher levels depend on lower levels for food.

Answer:

B. it shows that the lower levels are needed to support the higher levels