How does the small size of a spore its function? a) spores can travel far. b) spores provide structure. c) spores fit into a cell. d) spores are specialized.

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.