Answer: D. Water will enter and exit the cells at a steady rate and their sizes will remain the same.
Step-by-step explanation:
Osmosis occurs when the salt content is NOT the same as our red blood cells: the salt or lack of it causes our RBCs to swell or shrink. Isotonic fluid has the same salt content as our RBCs. This is why it's important to watch salt intake in congestive heart failure.