An investigation was designed to determine how freshwater fish maintain homeostasis within their environment. It was observed that the concentration of substances inside the fish cells was much higher than the concentration of substances in ponds, lakes, and streams and that freshwater fish have a constant flow of water from the environment into their cells. Based on these observations, in what type of environment must these fish live?
A
hypertonic
B
hypotonic
C
isotonic
D
osmotic