Which of these describes cell-
mediated immunity?
A. the binding of antigen and antibody triggering a
response of plasma and memory b-cells to attack
B. t-cells and macrophages fighting infected cells that are
non-self or cancerous
C. our body remembering pathogens it has fought off or
learning from vaccines
D. obtaining immunity from an outside source, like mother
to baby

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 .