C. A buildup of lactic acid in the tissues.
A theory which is tested again and again and found to fit the facts and from the valid predictions may be made is then known as scientif ic law or priciples..
Answer:
They live in or around freshwater ponds, lakes, rivers, marshes and swamps.
Explanation:
An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. ... By feeding on plants and on one-another, animals play an important role in the movement of matter and energy through the system.
