In a forest, the nitrates contained in the nucleic acids of a bear can be made available again to primary producers after the bear dies, through the action of: A Vultures that eat fat and muscle from the carcass B Bacteria that decompose organic molecules back to their inorganic components C The toxic mushroom that the bear ate, which killed it D The salmon that are an important food source for the bear

Option B

Explanation:

In any food cycle or ecosystem, the top most organisms are the decomposers. They are kept above the tertiary species because when the tertiary species die, these decomposers or micro-organisms feed on them and convert organic material with in them into reusable form/nutrients/chemicals.  

These nutrients get mixed with the soil and are reused by the plants and trees (producers) for making food for all other organism in the food chain by entrapping solar energy.  

Hence, option B is correct