The existence of life in the past in a certain region is suggested by beds of which one or more of the followi

Question

a. sandstone
b. marble
c. granite
d. graphite

Answer 1

Marble and Graphite

Brian is right about graphite. It's considered to be the highest grade of coal usually and formed from metamorphosis of originally organic material. But, you'd also have to include marble as an indicator of past life. Marble is metamorphosed limestone. Most limestone formed from the remains of marine organisms with calcium carbonate shells.

Answer 2

Hmm this is a difficult question, but I think I would have to go with D. Graphite is composed of carbon, which all organic matter is composed of. As the life dies it degrades back into the element, and if some way that layer of life is buried and exposed to both high pressure and temperature, it can crystallize into graphite.