In this task, you are given a question and answer for that. The answer will fill in the blank or will complete the unfinished question. Your task is to provide an explanation based on the given question or fill-in-the-blank statement, and answer.

[EX Q]: Question: Henry noticed that his piece of cake was lighter than his piece of butter. The cake was _____ dense. 
 Answer: less
[EX A]: A given volume of a denser substance is heavier than the same volume of a less dense substance.

[EX Q]: Question: Carol is building a small rocket to test in her back yard and, after much consideration, decides to use a biofuel to power her rocket. She tells her friends it's because it will create _____ carbon dioxide than fossil fuels. 
 Answer: less
[EX A]: The advantage to biofuels is that they burn more cleanly than fossil fuels. As a result, they create less pollution and less carbon dioxide.

[EX Q]: Question: Bryan was tasked with categorizing various fossils that the archeology team dug up. He knew they found some in rock layers near the surface and others in layers much farther below the ground. Which should he categorize as the older ones? 
 Answer: farther down fossils
[EX A]:
The main law is the law of superposition. This law states that deeper rock layers are older than layers closer to the surface.