Select the Answer That Corrects the Comma Splice or Run-On

Select the answer that corrects the comma splice or run-on sentence.
-Marty dreamed of being a star, therefore he auditioned almost every week.

A) Marty dreamed of being a star, therefore, he auditioned almost every week.
B) Marty dreamed of being a star, therefore; he auditioned almost every week.
C) Marty dreamed of being a star therefore he auditioned almost every week.
D) Marty dreamed of being a star; therefore, he auditioned almost every week.