From the information provided, the most accurate conclusion is:
D. Oil and natural gas can be found on land or underwater.
This conclusion aligns with the details that oil rigs can be built on land or offshore, indicating that oil and natural gas are located in both environments.
Regarding the description of the oil rig based on the image of divers performing inspections and repairs, you can state that it is a complex structure that requires regular maintenance and professional oversight to ensure safety and functionality.