"In Classical Conditioning,as in Telling a Good Joke,timing Is Critical

Multiple Choice

"In classical conditioning,as in telling a good joke,timing is critical." What did the authors of the textbook mean?

A) The CR and the UCR must be presented closely enough in time to be perceived as related.
B) The CR and the UCR must be presented far enough apart in time to be perceived as unrelated.
C) The CS and the UCS must be presented far enough apart in time to be perceived as unrelated.
D) The CS and the UCS must be presented closely enough in time to be perceived as related.