A passage and a problem

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I need some help for the passage below and problem for it.

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In the late 1960s, Paul Ekman took a trip to Papua New Guinea to conduct a series of interviews with the Fore, an isolated tribe living in an ancient, pre-literate culture. He was seeking to test the cultural theory of emotion: the idea that emotions are learned behaviors that are picked up from family and friends, like languages. According to this theory - which was almost universally accepted at the time - in order to experience joy or bitterness, you first need to see others being joyful or bitter. Without that social transmission, you would never experience those emotions.
Ekman’s experiment was remarkably simple: he told the Fore tribesmen various stories and then asked them to choose, from photographs of Americans expressing various emotions, the photo that most closely matched the story. One story, for example, involved coming across a wild animal in a hut, a situation that would create fear in Westerners. Given that the Fore had never had any contact with Westerners, Ekman did not expect them to have any idea about the kinds of emotions experienced by Westerners or the facial expressions associated with them. But to his astonishment he found that when they were shown the photographs, the Fore tribesmen picked out precisely the expressions that Westerners linked to the stories. Ekman then reversed the experiment, asking the Fore people to make facial expressions appropriate to the various stories, which he videotaped. After he arrived back in San Francisco, he asked Americans to link the Fore faces to the stories. Once again, the judgments coincided perfectly.

Which is the most suitable title of the passage?
? Emotions Are Present from Birth
? Negative Emotions Spread Fast
? Express Your Emotions; Don’t Hide Them
? How Should We Control Our Emotions?
? Emotions: The Result of Cultural Transmission