Fact 1: Cells secrete acids and bases to maintain the proper pH for enzymes to work.

Fact 2: Most human enzymes work at a optimal pH of 7.4, but other enzymes work at many different pH ranges.

Given the two facts above, answer the question "Cells secrete acids and bases to maintain what?" with the following options: 
- Chemical energy
 - resistance
 - increases a body's strength
 - To keep their body heat.
 - most human enzymes
 - aerobic capacity
 - allow growth
 - temperature


 

     most human enzymes    