Which sentence is written correctly?

• Ms. Praveena showed us a documentary in class today because the film, "focuses on a similar subject" to a book we are going to read.
• Ms. Praveena showed us a documentary in class today because the film "focuses on a similar subject" to a book we are going to read.
• Ms. Praveena showed us a documentary in class today because the film, "Focuses on a similar subject" to a book we are going to read.
• Ms. Praveena showed us a documentary in class today because the film "Focuses on a similar subject" to a book we are going to read.