Which material maintains the digestive environment in the stomach?
a strong bases
b weak bases
C strong acids
d weak acids

In which layer do organisms on earth love?

What term describes a doctor who becomes a specialist by meeting standards beyond those of getting a license and passing a test in the specialty area?

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.