Explain the proper use of the comma to set apart nonessential elements within a sentence

Nonessential elements are always offset with commas. The commas dictate a pause when you are reading the sentence or speaking it out loud. If the word, phrase or clause is easily removed from the sentence or moved to another spot within the sentence, the clause is set off with commas on each side. Likewise, if the element interrupts the flow of the sentence, offsetting commas are used.

Example: 

“However” is a nonessential word because it interrupts the flow of the sentence, requiring offsetting commas. It is also moved without changing the meaning of the sentence.

Commas are used as a signal to readers that a modifying element is not essential to their understanding of the sentence. Commas must be placed before and after the nonessential element when it appears in the middle of a sentence. For example: The Library of Congress, located in Washington, DC, has one of three original Gutenberg Bibles in its collection.

Explanation:

on edg.2020

where are the multiple choice answers?