The early lack of exposure to science ,technology,engineering and mathematics (STEM) can be harmful to achieving gender  balance in these fields. It begins when we are young and continues throughout our time in high school. While at home,girls generally don't get to experience the level of exposure or encouragement in STEM fields that their male counterparts do. It is often subtle ,but it's the first hurdle that faces and confuses so many women. Boys ,on the other hand, get on their path ,and are encouraged to do so, generally earlier than girls. For example ,boys are more often given science sets as toys ,which spark an interest in these subjects. In school3boys are often pushed to take the more challenging math and science classes. So if we want to attract the best and brightest minds into the fields that will advance us as a people?a country,and a planet,we can no longer look to only half of the population. Young girls cannot possibly consider opportunities they do not know exist. If girls are not exposed to certain subject and career paths,they are highly unlikely to choose to follow them in college. Our bias toward girls9either from families or from schools ,is so rooted in our culture that we often don't even recognize _ . Although the situation Has changed greatly in the past 20 or 30 years,there is still a sense that girls aren't as good at math9for instance9even though there is almost no evidence to support such a belief. It is important that as a society we deal with gender stereotypes long before young people are faced with a decision to declare or choose a major in college. Without making efforts to break them, we are limiting the potentials of our youth,both male and female. Providing the necessary resources, exposure,and encouragement would help young women understand that their gender shouldn't determine the career path they choose, and that pursuing a STEM career does not make them less feminine. The main purpose of the passage is to  _  .
show women's potentials in STEM fields praise women's contributions to STEM fields describe the present gender bias in STEM fields call for more involvement of women in STEM fields