Explain why eating only plants is more effiecent than eating meat

This is a biological reaction due to a stimulus. i need this quickly !

Ineed with a hypothesis my question is can seeds sprout in different locations?

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.