Which of the following is considered a norm?

The correct choice is centered on the definition of norms within a social context. Norms are informal understandings that govern the behavior of members within a society, group, or community. They reflect the values and attitudes that are considered acceptable or appropriate within that context. When a value or attitude is widely shared and upheld by a particular group, it becomes a norm that guides individuals' actions and interactions.

While legal guidelines and rules applied to institutions can influence behavior, they are different from norms in that they are formalized and enforced by institutions. Legal guidelines pertain to laws, while rules within institutions often have specific purposes outlined by organizational structure.

An economic structure, on the other hand, refers to how an economy is organized, including the types of economic systems in place, which is unrelated to the social behaviors and expectations represented by norms. Thus, the essence of what makes option B the correct choice lies in its representation of shared group attitudes and standards that shape individual behavior within a community.