If the pain in your knee continues, I advise... a doctor. a. you see b. to see c. you to see

The correct answer is b. to see.

The complete sentence would read: "If the pain in your knee continues, I advise to see a doctor." However, it is more common to say, "If the pain in your knee continues, I advise you to see a doctor." So, the phrase "you to see" is also correct in certain contexts.