instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: The bodies of organisms can make a sedimentary rock. Plant bodies are lithified to become coal. When shells are cemented together they make a type of limestone. So limestone can be considered chemical or organic. Answer: coal
answer:
What is formed when plant bodies are lithified?

question:
Passage: and procaine. Not only do catalysts greatly increase the rates of reactions, but in some cases such as in petroleum refining, they also control which products are formed. The acceleration of a reaction by a catalyst is called catalysis. Answer: reactions
answer:
Catalysts can greatly increase the rates of chemical what?

question:
Passage: All of these animal behaviors are important. They help the animals get food for energy, make sure their young survive, or ensure that they, themselves, survive. Behaviors that help animals or their young survive, increase the animals' fitness. Animals with higher fitness have a better chance of passing their genes on to the next generation. If genes control behaviors that increase fitness, the behaviors become more common in the species. This occurs through the process of evolution by natural selection. Answer: evolution
answer:
Fitness and natural selection are parts of what theory that might describe how organisms change over time?