Help me, my brain's under a rock and due in 5 minutes, late work

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.

Injuries in the environment are a result of

How do herbicide-resistant plants farmers? a.farmers can spray for weeds without killing the crops b.the plants kill the weeds c.the soil is enriched for future plantings