Minick Rosing's Analysis of Microscopic Globules of Carbon Found in Rocks

Multiple Choice

Minick Rosing's analysis of microscopic globules of carbon found in rocks 3.7 billion years old showed that they were somewhat higher in ¹²C as opposed to ¹³C.This is significant because ________.

A) ¹³C radiometrically decays into ¹²C, which lets us calculate the age of these rocks
B) life could not have arisen in an environment with excessive ¹³C
C) these carbon globules contain visible remains of cell walls and nuclei
D) living things that fix carbon preferentially incorporate ¹²C over ¹³C
E) meteorites must have brought ¹³C to the early Earth