单项选择题

TEXT A
American culture is defined by rather gradual movements from one stage of socialization to the next. The lifelong socialization process involves many different social forces which influence our lives and alter our self-images.
Family The family is the institution most closely associated with the process of socialization. Obviously, one of its primary functions is the care and rearing of children. We experience socialization first as babies and infants living in families; it is here that we develop an initial sense of self. Most parents seek to help their children become competent adolescents and self-sufficient adults, which means socializing them into the norms and values of both the family and the larger society.
The development of the self is a critical aspect of the early years of one’s life. In the United States, such social development includes exposure to cultural assumptions regarding sex differences. The term "gender roles" refers to expectations regarding the proper behavior, attitudes, and activities o{ males and females. As the primary agents of childhood socialization, parents play a critical role in guiding children into those gender roles deemed appropriate in a society. Other adults, older siblings, the mass media, and religious and educational institutions also have noticeable impact on a child’s socialization into feminine and masculine norms. Differential treatment of children by adults is an influential aspect of gender-role socialization. Let us consider a hypothetical example of differential treatment of children which begins in the family. Ron and Louise are twins who both show an unusual interest in science at an early age. For his birthdays, Ron is given chemistry sets, telescopes, microscopes, and the liked however, despite asking for similar gifts, Louise is given miniature dollhouses, beautiful dresses, and dancing lessons.
When the twins are in junior high school, teachers take note of Ron’s love for science. They encourage him to do special projects, to help with their laboratory work, and to join the science club. Louise is given no such encouragement; in fact, one teacher considers her fascination with astronomy "strange" for a girl. By the twins’ high school years, Ron is well known as a "science whiz". The guidance counselor suggests that he attend a college with a strong science program in order to achieve his goal of becoming a biologist. Louise has realized that she would like to become an astr0nomer, but the counselor and her parents pressure her into preparing for a career as an early childhood teacher—a career which they see as more suitable for a woman.
During their college years, Ron and Louise might develop self-images as "scientist" and "teacher", respectively. On the other hand, Louise might get to college, switch her major, and become an astronomer despite everyone’s opposition. Neither of these young people is a passive actor who will inevitably follow the traditional gender roles of American society. Yet it can be extremely difficult to pursue a career, or any other type of life choice, if one’s parents, teachers, and the society as a whole seem to be telling you that you are unmasculine or feminine for doing so. Without question, differential socialization has a powerful impact on the development of American females and males.
Like other elements of culture, socialization patterns are not fixed. There has, for example, been a sustained challenge to traditional American gender-r01e socialization in the last 15 years, owing in good part to the efforts of the feminist movement. Nevertheless, despite such changes, children growing up in the 1980s are hardly free of traditional gender roles.
As can be inferred from the passage, gender-role socialization patterns ______ in the United States.