Question 1. The right option is A- response.
The characteristic of life that this behavior best illustrate is response.
A response is any reaction or behavior of a living organism to an external or internal stimulus. From the question given, the desert tortoise is having a response to the environmental factors.
Question 2. The right option is D-Desert pack rats are active at night to conserve water.
The statement; Desert pack rats are active at night to conserve water best illustrates how an organism maintains homeostasis.
Homeostasis is the ability of living organisms to adjust to their internal environment inorder to maintain a stable or balanced equilibrium.