Answer: A. cold temperature + C. pressure + D. absence of oxygen
Explanation: The conditions required to convert the body fluids and gases of dead and buried microscopic organisms into petroleum are cold temperature, pressure, and absence of oxygen. These conditions allow the organic materials to be preserved and transformed over millions of years into fossil fuels like petroleum. Moisture and lots of oxygen would actually hinder the formation of petroleum by promoting the growth of microorganisms that break down organic matter.