Which statement is true for both electrical magnet waves

Explain how fossils scientists make discoveries about the lives of organisms and about how environments have changed over time. plz hurry up it time

[34 points awarded to the best answer, use facts and/or data] 1.) what's the likelihood of thunderstorms occurring in the state of maryland? {this question is for a project for science, use facts and/or data and explain why . 34 points to the best answer]

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.