Answer:
Your answer would be that a comma cannot be used to correct most run-on sentences.
Explanation:
If you add only a comma to a run-on sentence, you are likely to turn it into a comma splice. A run-on sentence occurs when two or more independent clauses are not joined correctly. There are two types of independent clauses: fused sentences and comma splices.
Fused sentences occur when independent clauses run together with no marks of punctuation or coordinating conjunctions to separate them (1). However, adding a comma to separate the independent clauses would create another problem: the sentence would have a comma splice. A comma splice occur when two or more independent clauses are joined only by a comma (2).
1) My mother read my new novel she said it was excellent
2) My mother read my new novel, she said it was excellent
In order to fix these mistakes, you could add a comma and a coordinating conjunction or you could use a semicolon (3; 4).
3) My mother read my new novel, and she said it was excellent
4) My mother read my new novel; she said it was excellent
