The act of breathing raises the blood oxygen level, lowers the blood carbon dioxide concentration, and raises the blood pH. According to the principles of negative feedback, sensors that regulate breathing should respond to_________a. a rise in blood oxygen.b. a rise in blood pH.c. a rise in blood carbon dioxide concentration.d. all of these.

The feedback regulation may be defined as the process in which the end product of the metabolic pathway regulates the homeostasis of the body. Two main types of feedback are positive feedback and negative feedback.

The negative feedback mechanism occurs when the end product of the reaction is responsible for the shutdown of the metabolic pathway and decreases its concentration. The breathing is controlled by the negative feedback mechanisms, the increase in carbon dioxide concentration acts as the negative sensor as this sensor is mainly responsible for the increase in amount of oxygen level and maintain homeostasis of the body.

Thus, the correct answer is option (c).