My dog has his own bed he sleeps on the couch when no one is looking, though. Which of the revisions corrects the sentence?

a. My dog has his own bed. He sleeps on the couch when no one is looking, though.
Ob. My dog has his own bed, he sleeps on the couch when no one is looking, though.
Oc. My dog has his own bed he sleeps on, the couch when no one is looking, though.
Od. My dog has his own bed; He sleeps on the couch when no one is looking, though.
Clear my choice