Use the information and graph to answer the following questions what conclusion can be drawn

What do nitrifying bacteria convert

As a result of these processes the single celled organism accomplishes

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.