Questions: A vertebrate that lays a hard-shelled amniotic egg, has feathers for flight and insulation, and is endothermic is called a thecodont, mammal, bird, pterosaur.

The answer is the third one (C): bird.

Explanation for each option:

• Thecodont: Thecodonts are an extinct group of reptiles that are not known for laying hard-shelled amniotic eggs, having feathers, or being endothermic. Therefore, this option is incorrect.

• Mammal: Mammals are endothermic vertebrates, but they do not lay hard-shelled amniotic eggs or have feathers. Instead, they give birth to live young (with a few exceptions like the monotremes) and have hair or fur. Thus, this option is incorrect.

• Bird: Birds are vertebrates that lay hard-shelled amniotic eggs, have feathers for flight and insulation, and are endothermic. This description matches the characteristics given in the question, making this the correct answer.

• Pterosaur: Pterosaurs were flying reptiles that lived during the time of the dinosaurs. While they had some adaptations for flight, they did not have feathers and are not considered endothermic in the same way birds are. Therefore, this option is incorrect.

In summary, the vertebrate described in the question is a bird.