Answer
D. Both b and c are correct..
Work Step by Step
The respiratory system regulates pH balance by managing the amount of carbon dioxide ($CO_2$) in our blood. When $CO_2$ mixes with water in our bodies, it breaks down into carbonic acid ($H_2CO_3$), which causes our blood to become more acidic.
The kidneys, part of the urinary system, help to regulate pH balance by increasing or decreasing acid secretion in the body and by managing levels of dietary acid in the body.
