You are presented with the quiz "What is a product of layers of sediment pushing down on decomposing algae over time?" 

But you don't know the answer, so you turn to your teacher to ask for hints. He says that "oil is formed by layers of sediment pushing down on decomposing algae" and "fossil fuels like coal and oil are ancient biomass fuel". 

So, what's the best answer to the question?


 

   Fossil fuels        