The autonomic nervous system controls all responses of the body. a. unconscious b. voluntary c. sequenced d. repeated

A. unconscious

It's A because it controls the involuntary actions like our heart beat or breathing. The actions we aren't consistently remembering to do.  

the answer is lactic acid from anaerobic respiration. the acid in lactic acid is what creates sore and burning muscles. if you think about how acid burns that will give you a clue for questions like this.