Most likely audience and purpose. It's not like there are timed applications and the way you write it is up to as long as it makes sense.
Your were right, it is the first one.
Ted Kerasote introduces the setting in the first paragraph of his essay. He describes the scene to the reader, that the action is taking place in the Northeastern corner of Yellowstone Park in the hills above Soda Bottle Creek. He describes that it's an isolated area, if you left one road you would not come across another one for quite some time.
To use another person's work without giving credit where credit is due
