The students read many books, piles lay all around the library.
Option A is correct. Change the comma to a semi-colon.
The semicolon is a punctuation mark that devides major sentence elements. A semicolon can be placed between two closely related independent clauses, provided they are not already connected by a coordinating conjunction. Moreover, semicolons can be used in place of commas to separate items in a list, particularly when the elements of that list contain commas.