Frog lungs have a smaller surface area for gas exchange than mammalian lungs. How do frogs compensate for this difference? a. Frog tissue absorbs more oxygen from the blood than mammalian tissue does. b. Frogs breathe more quickly than mammals. c. Frogs also obtain oxygen via diffusion across the skin. d. Frog lung tissue has a greater density of capillary beds than mammalian lung tissue.