An organic carbon compound is contaminating a groundwater aquifer. It is biodegradable under both aerobic and anaerobic conditions, but the oxygen in the groundwater has been depleted. According to thermodynamics, which electron acceptor will be most favorable for growth of microorganisms on this organic compound

Which of the following statements is most likely correct about a rock belonging to the jurassic age and a rock belonging to the cambrian age? options: 1) they have identical fossils of organisms that have evolved over time. 2) both have animal fossils preserved in them due to weathering and erosion. 3) they contain different fossils because life on earth has changed through time. 4) the fossils in them were formed on the surface of earth due to exposure to sunlight.