The following sentence contains an introductory phrase:
It may sound crazy but fatty fish is one of the healthiest things you can eat.
Which revision correctly punctuates the sentence?
It may sound crazy but, fatty fish is one of the healthiest things you can eat.
It may sound crazy, but fatty fish is one of the healthiest things you can eat.
It may sound crazy but fatty fish is one of the healthiest things, you can eat.
It may sound crazy, but, fatty fish is one of the healthiest things you can eat.