Which behavior in a client with schizophrenia demonstrates the client's cognitive inability to appropriately process data from external stimuli?

The answer would be delusional beliefs

Schizophrenia is caused by high amount of dopamine inside the brain. It can cause the patient to percept something when there is no external stimulus taken(it different with the illusion where the external stimulus exists but perceived wrongly).
They also couldn't process the external stimuli, resulting in delusional beliefs. 

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.

It starts at stage three hop this