21. In what ways are lungs and gills similar? A. Both are used for circulating blood through the body.
B. They both are used in animal mating behavior.
C. Both are organs animals use to exchange oxygen & carbon dioxide.
D. None of the above.

Chloroplasts and bacteria are in size. a. similar b. at different ends of the size range c. exactly the same d. none of these

Which statement is true about the two stars labeled in this diagram?

Which statement is true regarding weathering in dry environments? a) chemical weathering is absent because of a lack of humidity. b) physical weathering is usually more evident than chemical weathering. c) it is impossible to identify the type of weathering that has occurred. d) physical weathering does not play a significant role in dry environments.