The widely accepted biogenic theory of petroleum formation suggests that crude oil originated from which primary sources accumulated over geologic time?

Introduction:
The origin of petroleum is central to geology and refining. The mainstream biogenic model holds that crude oil derives from ancient biological materials that underwent transformation under heat and pressure in sedimentary basins.

Given Data / Assumptions:

• Source materials: organic remains from marine and lacustrine environments.
• Processes: burial, diagenesis, catagenesis.
• Outcome: kerogen formation and subsequent generation of oil and gas.

Concept / Approach:
Both microscopic plants (algae, phytoplankton) and animals (zooplankton) contribute organic detritus. Over time, oxygen-poor conditions preserve this material, forming source rocks; thermal maturation then yields hydrocarbons expelled into reservoirs.

Step-by-Step Solution:
1) Identify the biogenic hypothesis: organic precursors drive petroleum formation.2) Recognize both plant and animal plankton contribute significant carbon.3) Select the option that includes both sources.

Verification / Alternative check:
Geochemical markers (biomarkers, isotopic signatures) trace back to biological origins, supporting the mixed plant–animal source model for most crude oils.

Why Other Options Are Wrong:
Plant only / animal only: Incomplete; both contribute.Neither/ inorganic: Contradicts biomarker evidence.Mineral oxides: Not organic precursors for petroleum.

Common Pitfalls:
Overemphasizing a single source (e.g., only algal) and ignoring zooplankton; many source rocks reflect mixed organic inputs depending on the paleoenvironment.

Final Answer:
Both plant and animal organic matter