Answer: The comma attempts to join two independent clauses.
Step-by-step explanation: A lone comma is not enough to join two independent clauses (i.e., clauses that can stand by themselves as complete sentences). To keep the comma, you must add a conjunction after it (e.g., so); otherwise, the comma should be replaced by a period (capitalizing the second sentence) or a semicolon (leaving the second sentence uncapitalized).