Which sentence is written correctly? as an enthusiastic reader, sanjay often visits the library to check out new books. as an enthusiastic reader—sanjay often visits the library to check out new books. (as an enthusiastic reader) sanjay often visits the library to check out new books. as an enthusiastic reader sanjay often visits the library to check out new books.

the first one:As an enthusiastic reader, Sanjay often visits the library to check out new books. hope I helped

The correct option is the first one: As an enthusiastic reader, Sanjay often visits the library to check out new books.

Explanation:

Commas, that commonly indicate soft pauses into sentences, have many situations in which they need to be used. Among such situations highlight comma after introductory phrases, as is the case in the particular example provided.  

It is possible to notice that, in the sentence shown, a comma is being used to follows the adjective phrase that introduces the sentence. That is to say, in the example given comma is being used after an introductory phrase.  

That is why, it would be correct to state that, from all the sentence choices provided, the one that is written correctly is:  As an enthusiastic reader, Sanjay often visits the library to check out new books.

600 dollars if i'm not mistaken.