A: Some energy will be used to do work and some will be lost as heat.
Explanation:
According to the second law of thermodynamics, none of the processes of energy transformation is 100% efficient. The part of the energy is always converted into unusable form and is lost as heat.
Consumption of food includes process of cellular respiration to obtain energy from nutrients. However, part of the energy of nutrients is lost as metabolic heat and rest are stored in the form of ATPs.
Example: during cellular respiration, only 40% energy of a glucose molecule is stored in form of ATPs and rest 60% is lost as heat.
