2 Describe Your class has taken a field trip to a local stream. You notice that the rocks in
the water are rounded and smooth. Write a
brief description of how you think the rocks
changed over time.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.

the answer you are looking for is d. there are no holes for blood to enter or leave the system. your welcome