What is the correct answer?

When water freezes, it . contracts expands

Which of the following describes a boom period? a. as one population increases, another population decreases. b. as one population increases, the other population also increases. c. as one population decreases, another population increases. d. as one population decreases, another population also decreases

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above