While Science Is Not Yet Able to Describe the Phenomenon

While science is not yet able to describe the phenomenon of "thinking" in physical terms,we can be certain that it is a process involving the metabolism of brain cells.With positron emission tomography (PET scan) it is possible to inject short-lived isotopes and image the regions of the brain that have the most active metabolism during various mental activities.For different mental functions,different regions and amounts of nerve cells become active.However,

A) the cellular energy expended in "thinking" must be less than the chemical bond energy supplied in food to these brain cells.
B) "thought" cannot be linked to cell processes because energy is not related to matter.
C) since thoughts can occur over and over,the requirement for a continual input of energy to prevent entropy does not apply to this cell activity.
D) "thinking" is beyond the scope of science to study.