An air environment, gravity, and desiccation are three challenges that were addressed in the evolution of reptiles. What three evolutionary innovations addressed these challenges?

The three evolutionary innovations that addressed these challenges were lungs, better limb support, and the amniotic egg.

Explanation:

Due to an air environment with a high gravity force and lack of humidity reptiles had to adapt to the new conditions with the presence of lungs that allow them to use the oxygen in the air environment to survive, as well as better limb support that helped them to move from one place to another against the gravity force and amniotic eggs that allows them to grow in an environment where they have the necessary nutrients and protection when they are still not ready for the air environment and its gravity force.

the cell cycle is the final answer! : )