'Read and win' contest: question #3

All right, here's the third question in the "Read and win" contest series.
The same rules apply — first person to email me (karen@oakpress.com) with the correct answer will get to choose a prize from this list of available prizes.

Today's question has been answered. Deb Runyan of Commerce Township is the winner, for a third time! She answered correctly, choosing number 5. 

As with the first two questions, the answer can be found in one of these three posts:
Behavior 101: Shaping vs. training, Part I
Behavior 101: Shaping vs. training, Part II
If the dog likes you, I like you

I will update this post as soon as the question has been answered correctly by someone.

Today's question is multiple choice. Here it is:

Dog owners are famous for allowing their dogs to have an opinion about people they meet, and giving that opinion credibility — call it the, "If the dog likes you, I like you" mentality. Why does this happen?
1. Dogs are incredible readers of human body language and are frequently quite good at picking up on a person's trustworthiness based on general body language cues.
2. The confirmation bias — the dog studies its owners response to a person and reacts accordingly.
3. Dogs have a sixth sense that guides them in determining the general goodness of a person.
4. Answers 1 &3.
5. Answers 1 & 2.