Final answer:
The normal pH of blood is 7.4, indicating that it is slightly alkaline and regulated by biological buffers to maintain homeostasis.
Step-by-step explanation:
The normal pH of blood is 7.4, which means the correct answer to the student's question is C. 7.4.
The pH scale ranges from 0 to 14, where a pH less than 7 is acidic and a pH greater than 7 is alkaline. Pure water, being neutral, has a pH of 7.0.
Blood is slightly alkaline, and its pH is tightly regulated to stay within a narrow range of 7.35 to 7.45, with the average pH being 7.4, due to the importance of maintaining homeostasis.
This balance is achieved by buffers like the bicarbonate system, which help to neutralize changes in acidity or alkalinity and keep the body functioning properly.