The correct answer is Sentence 5
Step-by-step explanation:
In writing, a run-on sentence is a type of grammatical and punctuation mistake that occurs when a sentence contains two or more independent clauses and there are not separated correctly either because there is no punctuation between them or because a comma is placed instead of a semicolon (;) which is the punctuation mark that should be used to separate this type of clauses. The first case described can be seen in sentence 5, because this contains two independent clauses (clauses that express a complete idea) "With these improvements, skateboarding became more popular than ever" and "in fact it became a worldwide sport" but these have not been separated neither by using semicolon or a transition word, which makes this an example of run-on sentence.