Answer:
B. It is given off as heat.
Step-by-step explanation:
Organisms feed on one another in an ecosystem in order to gain energy needed for their life processes. This feeding pattern is termed FOOD CHAIN. Each organism occupies a position in the food chain depending on the pattern of their feeding behavior. This level is called TROPHIC LEVEL. So, the food chain progresses when one organism in a particular trophic level feeds on another organism in a lower trophic level.
As organisms in each trophic level feeds on another, only about 10% of the energy is available to that organism. This is because majority of the energy (about 90%) has been lost as heat when organisms engage in their metabolic activities. For example, a producer which starts a food chain obtains energy by producing its own food via photosynthesis, it is fed on by a goat in the next trophic level. Only 10% of the total energy is available to the goat because 90% of the energy has been lost via heat when the plant undergoes metabolic activities.