They lay eggs because they don't have the genetics or things in their body to give birth.
Answer: Water can hold an unlimited amount of oxygen.
Explanation:
Water cannot hold an unlimited amount of oxygen because it would get to a point where it is saturated as it needs to hold Hydrogen as well. Air on the other hand, has significantly more space for oxygen as it contains only 21% and can keep taking more.
Underwater organisms need oxygen for respiration and a small decrease in the oxygen available in water affects aquatic life because they rely on it to survive.
