Explanation:

- Option 1: You look

This part is grammatically correct. It's the beginning of a sentence, introducing the subject and verb properly.

- Option 2: to bed now

This segment is logical as a destination and timing, pairing well with an action verb.

- Option 3: you would go

This segment contains the error. "Would" implies conditional or future intentions. The correct phrase should be "should" or "ought to," suggesting a recommendation.

Correct Answer: Option 3 - you would go

- Option 4: very tired

This part accurately describes the subject's state and is grammatically correct.