In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").

Fact1: oil is formed by layers of sediment pushing down on decomposing algae, Fact2: Fossil fuels like coal and oil are ancient biomass fuel., Question: What is a product of layers of sediment pushing down on decomposing algae over time? (A) Fungus (B) Greenhouse gases (C) Fossil fuels (D) Calcium carbonate (E) salinity (F) Sand (G) contamination (H) Water
C