Final answer:
Camels stay above ground in desert conditions thanks to their insulation, whereas kangaroo rats retreat underground due to less effective heat resistance. The correct option is c.
Step-by-step explanation:
The ability of camels to stay above the ground under daytime desert conditions, while kangaroo rats retreat below ground, is attributed to insulation (option c). Insulation refers to the camel's thick fur and fat layers which help protect it from extreme heat, allowing it to withstand higher temperatures without needing to seek cooler areas.
In contrast, the kangaroo rat possesses adaptations like highly efficient kidneys that produce concentrated urine to minimize water loss, but lacks the same level of insulation, forcing it to avoid the daytime heat by going underground. The correct option is c.