单选题 .  People have wondered for a long time how their personalities and behaviors are formed. It is not easy to explain why one person is intelligent and another is not, or why one is cooperative and another is competitive.
    Social scientists are, of course, extremely interested in these types of questions. They want to explain why we possess certain characteristics and exhibit certain behaviors. There are no clear answers yet, but two distinct schools of thought on the matter have developed. As one might expect, the two approaches are very different from one another, and there is a great deal of debate between proponents of each theory. The controversy is often referred to as "nature/nurture".
    Those who support the "nature" side of the conflict believe that our personalities and behavior patterns are largely determined by biological and genetics (遗传学) factors. That our environment has little, if anything, to do with our abilities, characteristics, and behavior is central to this theory. Taken to an extreme, this theory maintains that our behavior is predetermined to such a degree that we are almost completely governed by our instincts.
    Proponents of the "nurture" theory, or, as they are often called, behaviorists, claimed that our environment is more important than our biologically based instincts in determining how we will act. A behaviorist, B. F. Skinner, sees humans as beings whose behavior is almost completely shaped by their surroundings. The behaviorists' view of the human being is quite mechanistic; they maintain that, like machines, humans respond to environmental stimuli (刺激) as the basis of their behavior.
    Either of these theories cannot yet fully explain human behavior. In fact, it is quite likely that the key to our behavior lies somewhere between these two extremes. That the controversy will continue for a long time is certain.1.  Which one of the following statements would supporters of the "nature" theory agree with? ______