Final answer:
Energy returns to primary producers after the death of consumers through decomposition, a process conducted by decomposers. The nutrients are cycled back to the soil and made available to primary producers, despite there being multiple steps in decomposition and nutrient recycling.
Step-by-step explanation:
The question asks about how energy returns to primary producers after the death of primary, secondary, and tertiary consumers. The energy is transferred back through a single fundamental process known as decomposition, performed by decomposers who break down dead organisms and return nutrients and energy to the soil, which in turn can be utilized by primary producers. So, there is effectively one main way for energy to be transferred back to primary producers after consumers die.
Producers, such as plants, are on the 1st trophic level, while primary consumers (herbivores), secondary consumers (carnivores that eat herbivores), and tertiary consumers (carnivores that eat other carnivores) are on the 2nd, 3rd, and 4th trophic levels, respectively. When these consumers die, the nutrients they have accumulated are broken down by decomposers like bacteria and fungi. Thus, the correct answer is B) Two, referring to the processes of decomposition and nutrient cycling, which includes both the physical breakdown and chemical transformation of organic material into forms that are accessible to primary producers.