Which of the following is a run-on sentence? a. the game was tied at halftime; each coach gave his team a pep-talk. b. the game will be called if the storm continues, the weather is dangerous. c. the players continue to work on both hitting and fielding, allowing them to improve both skillsets. d. while the rain was drenching at times, the fans were dedicated and refused to leave.

The correct answer is B. The game will be called if the storm continues, the weather is dangerous.
A run-on sentence is a grammatically incorrect sentence where two or more clauses are connected without using an appropriate conjunction, or without a conjunction at all. As you can see in sentence B, we have two clauses (the game will be called if the storm continues and the weather is dangerous) which are ungrammatically connected with just a comma.