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Answer:
The answer is A. shale.
Step-by-step explanation:
Shale is a fine-grained sedimentary rock that is typically formed from mud.
It is a good source rock for oil because it contains a high percentage of organic matter.
The organic matter in shale is derived from the remains of dead plants and animals that settled to the bottom of lakes and oceans millions of years ago.
As the shale is buried deeper and deeper, the heat and pressure cause the organic matter to break down and form oil and gas.