Answer:
The characteristic that is common to "all three groups of reptiles" is that they are all ectotherms.
Step-by-step explanation:
- Almost all the reptiles are referred to as 'ectotherms' because they are all cold-blooded.
- They adjust their body temperature according to the temperature of the surrounding.
- Reptiles like snakes do not have claws or eyelids. Moreover, not all reptiles protect their eggs.
- The "sea turtles" lay eggs on the seashores and go back to the seas.
- Thus, the only common characteristic among all the reptiles is that they are all ectotherms.