When the memory cells of the immune system are not activated or responding to a pathogen exposure?

Many kangaroo rats live in the sonoran desert of the southwestern united states. they have a variety of adaptations for living in the desert. under which circumstance would the kangaroo rats of the sonoran desert be most likely to develop new adaptations by natural selection?

Which description provides the best objective summary of the article in the passage?

Most of the carbon on earth is stored in the form of