What is true about an ecosystem?

1. A

   Primary consumers are least dependent upon producers

   Primary consumers (herbivores) depend directly on producers for food. They are not ‘least dependent’ on producers, so this statement is false.

2. B

   Primary consumers outnumber producers

   In a typical terrestrial pyramid of numbers, producers outnumber herbivores. Primary consumers do not outnumber producers in the textbook grassland case this item uses, so (b) is wrong.

3. C

   Producers are more numerous than primary consumers

   Producers are more numerous than primary consumers in the usual ecological pyramid of numbers. Green plants form the broad base; herbivores are fewer. That is the true statement and the official key.

4. D

   Secondary consumers are the largest and most powerful

   Secondary consumers are not always the largest or most powerful organisms; size and trophic level are different ideas, and a pyramid of biomass/energy does not make carnivores ‘largest’. This option is false.

Summary. Official key is (c). A standard pyramid of numbers has more producers than primary consumers. Herbivores depend on producers; they do not outnumber them in that model.