Answer:
The environment challenges him by making him dehydrated and both mentally and physically hurt. “Uncle cautioned him to make the water in his gourd last as long as possible. It was the hardest thing Salva had ever done, taking only tiny sips when his body cried out for huge gulps of thirst-quenching, life-giving water.
Answer: C. That dog gets fatter every day.
Explanation: All of the other answer choices are redundant; i.e. "most loudest", "more fuller" and "most quickest" do not work.