Question

Which sentence is a run-on sentence? A. Have you seen starfish or jellyfish on the beach? B. People breathe oxygen; fish do, too. C. A giant clam grows huge, it can weigh hundreds of pounds. D. When you fish, do you use worms as bait?

Answer 1

Option C contains a run-on sentence (I would call it a comma splice).

A better way to phrase the sentence could be:

1. A giant clam grows huge; it can weigh hundreds of pounds.

2. A giant clam grows huge.  It can weigh hundreds of pounds.

Answer 2

 The answer is C. A giant clam grows huge, it can weigh hundreds of pounds.