Human behavior is the very manifestation of the individual’s method of adjusting to his environment. In the study of human behavior, there are three prevailing theories, each stressing the impact of a particular aspect. The most recent of the three is the social learning theory which states that all behavior is the result of conditioning. Another theory, the psychoanalytical theory, depicts man at the mercy of his unconscious thoughts and motives. The third theory, the oldest of the three, the physiological theory, advocates the importance of heredity and physical characteristics in behavior development. According to the physiological theory, some people are mainly “digestion-minded,” some are “muscle-minded,” and some “brain-minded,” and correspondingly digestion-bodied, muscle-bodied, or brain-bodied. The digestion-bodied people look thick; the muscle-bodied people look wide, and the brain-bodied people look long. For the third kind of people, it does not mean that the taller a man is the brainier he will be. Instead, it means that if a man, even a short man, looks long rather than wide or thick, he will often be concerned about what on his mind than about what he does or what he eats; but the key factor is slenderness and not weight. On the other hand, a man who gives the impression of being thicker, rather than long or wide, will usually be more interested in a good steak than in a good idea or a good long walk. If a man is definitely a thick type, rather than a broad or long type, he is likely to be round and soft, with a big chest but a bigger belly. He would rather eat than breathe comfortably. People of this kind like other people, they are easygoing, and their feelings are easy to understand. In contrast, if a man is definitely a broad type rather than a thick or long type, he is likely to have lots of muscle. Such people would rather breathe than eat. They go in for adventure, exercise, fighting and getting the upper hand. They love to master the people and things around them. As for people of the third type, they are likely to have thin bones and muscles. Though such people are jumpy, they like to keep their energy and don’t fancy moving around much. They would rather sit quietly by themselves, and keep out of difficulties. Trouble upsets them, and they run away from it. They would easily become anxious, and they don’t get along well with other people in the sociable and aggressive world. According to the passage, which of the following statements is true?