Question

Which sentence is correctly punctuated? Gerbils’ teeth grow continuously, therefore; gerbils need to chew daily to keep their teeth short. Gerbils’ teeth grow continuously, therefore, gerbils need to chew daily to keep their teeth short. Gerbils’ teeth grow continuously; therefore, gerbils need to chew daily to keep their teeth short.

Answer 1

"Gerbils’ teeth grow continuously; therefore, gerbils need to chew daily to keep their teeth short."

Answer 2

The answer to your question would be that the sentence that is correctly punctuated is the following one: Gerbils' teeth grow continously; therefore, gerbils need to chew daily to keep their teeth short.

You should use a semicolon before "therefore" when it is introducing a complete sentence. Moreover, it is convenient to use a comma after it.