In a forest ecosystem, a pyramid of biomass is upright. If $P$ is at the highest trophic level, $Q$ is at the second trophic level, and $R$ is at the lowest trophic level, identify $P, Q,$ and $R$ from the following options.

• A
  $P$: Top Carnivores, $Q$: Herbivores, $R$: Producers
• B
  $P$: Producers, $Q$: Herbivores, $R$: Top Carnivores
• C
  $P$: Herbivores, $Q$: Producers, $R$: Top Carnivores
• D
  $P$: Top Carnivores, $Q$: Producers, $R$: Herbivores