I'm not positive but i would say B
It would be the energy source of "fossil fuel" that is formed when organic matter is trapped underground without exposure to air or moisture, since this material is eventually fossilized.
According to the attached image, the primary source was created Just after Austria-Hungary declared war on Servia (Serbia)
<h3>What is A primary Source?</h3>
In history, a primary source refers to the first account of an event which is narrated by people who were present when such an event occurred.
The primary source of an event is the most direct evidence of a time an event happened and is usually devoid of twists because such events are narrated as truthful as possible.
Learn more about a primary source at brainly.com/question/896456
#SPJ1
I do not know the answer but I think it might be D. or A.
Answer:
The answer is C.
Explanation:
It is tangible boundaries (C) because these are natural/physical limitations. The other answers would mean that they were marked or created by humans.
