Hello there!
Well, after taking this question, I figured I actually had the correct answer. When speaking about foreshadowing. Which is a clue or an idea of something that will be explained or presented in the future. Therefore, we would have to look for a answer that would have a 'surprise' feeling into it, if that were to make any sense.
Your answer: It helps create surprise when it turns out that Silky Bob is not as sharp or clever as he claims to be: he did not recognize Jimmy as the policeman who spoke to him.
We see in this option above, which is your correct answer, we see that it clearly says that 'it helps create surprise when it turns...". So, we see that it is surely a future reference that was actually not explained earlier.
Therefore, your option of answer would be the very first one, option A.
I hope this helps you!