The mast fundamental group to which a person belongs is the family. The institution of the family exists in almost every human culture. It is considered by behavioral scientists to be one of the oldest institutions in human history.The family unit serves many important functions. The performance of these functions is the reason for the family’s importance. Above all, the family serves as a mechanism of species survival.Families also have important economic functions. In primitive societies, the tasks of gathering food and providing shelter were divided among family members. Today, both husband and wife may work and share the duties of homemaking and child mating.In addition to its survival and economic functions, the family gives its members social status. In many societies, a person is not considered a complete member until he has married and produces children. Finally, the family helps to meet the basic emotional needs of a person through the love and support received from parents, siblings(兄弟姐妹) and relatives. Based on the information in the passage, you can infer that the passage is（）

A. about the family’s mechanism of species survival
B. about the social, economic, and emotional usefulness of the family throughout human history
C. about duties of the family shares by both husband and wife
D. about the emotional needs received from parents, siblings, and relations