Which statement accurately describes the relationship between the brain and addiction? a. normal activities produce heightened responses once receptors are reduced.
b. a higher amount of addictive chemicals are needed to get the same high when fewer receptors are present.
c. the brain reacts to excessive dopamine levels by increasing the number of dopamine receptors.
d. all drugs act on dopamine synapses in the same way.

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .