The example that shows an organism that cannot reach homeostasis through internal changes is:
A lizard is cold, and it moves to a sunny rock to warm up.
This indicates that the lizard is relying on external environmental factors (moving to a sunny rock) to regulate its body temperature, rather than making internal adjustments to achieve homeostasis. Lizards are ectothermic (cold-blooded) and do not internally regulate body temperature like endothermic organisms (warm-blooded animals) do.