Answer:
Mean sea level (MSL) (often shortened to sea level) is an average level of the surface of one or more of Earth's bodies of water from which heights such as elevation may be measured.
Explanation:
Lots of resources are located in the United States. Such as oil, gold, silver, iron, and much more.
Explanation:
A true friend would care about you like nobody else would they would always tell the truth to you or someone they would never lie to you the way they are acting can help identify too
It is definitely not a primary source: this would be a book itself.
Now, is it a tertiary source? I don't think so: the author of the review should have read the book and should only be referring to this book in the review.
I think it's a secondary source.
