The correct answer is C. I am surprised by you.
The sentence “You surprise me” is in the active voice, which means that the subject of the sentence (you) is doing the action (surprising). The passive voice would be “I am surprised by you,” which means that the subject of the sentence (I) is receiving the action (being surprised).
The other options are incorrect because they do not accurately reflect the meaning of the sentence. Option A, “I am to be surprised,” is in the passive voice, but it does not specify who is doing the surprising. Option B, “You surprised,” is in the active voice, but it does not specify who is being surprised. Option D, “He is surprised,” is in the active voice, but it does not specify who is doing the surprising.
In conclusion, the correct answer to the question “You surprise me” is C. I am surprised by you.