Consider the following biomes: Tropical Rainforest $(P)$; Tundra $(Q)$; Desert $(R)$ and Coastal zone $(S)$. The most probable order of Net Primary Productivity of these biomes is

The following word diagram depicts a food chain in a forest.

$$ \text { Trees (Aspen, willow) } \rightarrow \text { Herbivore (Elk) } \rightarrow \text { Predator (Wolf) } $$

Which is the most likely outcome of depletion in predator population?