Identify the source of energy from the given features A and B: A. It is a conventional source of energy. B. This source of energy is released when crude oil is brought to surface.

Natural gas is a conventional energy source and is often found along with petroleum (crude oil) deposits. When crude oil is brought to the surface, natural gas is released alongside it. Biogas is a non-conventional source, geothermal is unrelated to oil, and wax is not an energy source.