What are the lines on a weather map that connect places of equal pressure called?

Which of the following is not a challenge to instituting sound global environmental policies? a. most changes are inexpensive and easy to implement. b. elected leaders who support unpopular environmental issues often are not re-elected. c. economic considerations outweigh environmental ones in many societies. d. there is no way to enforce international environmental agreements.

Ineed , i need to create a power point in life science here is a picture explaining a little what the topic is about, me with some information for my slides : (

C. how would an erratic boulder provide evidence of the flood? type your response here: i