Which of Sutherland's 9 propositions is considered to be the most important proposition for explaining differential association theory, the proposition which explains the differential association mechanism? Proposition 3: The principal part of the learning of criminal behavior occurs within intimate personal groups. Proposition 6: A person becomes delinquent because of an excess of definitions favorable to violation of law over definitions unfavorable to violations of law. Proposition 7: Differential associations may vary in frequency, duration, priority, and intensity. Proposition 9: While criminal behavior is an expression of general needs and values, it is not explained by those general needs and values, since noncriminal behavior is an expression of the same needs and values