Respuesta :
Comma is used incorrectly in the sentence The Great Hall is open to the public, you must reserve a spot in advance because it attempts to join two independent clauses. Instead of a comma, you should use a semi colon here.
Answer: The comma attempts to join two independent clauses.
These two sentences are independent clauses. We know this because they both have a subject and a predicate (including a verb). These sentences would work better if they were separated by a period. Alternatively, they could also be joined by a semicolon.