1. The United Nations introduced the 17 Sustainable Development Goals in 2015. One of which is gender equality, and it states that "gender equality is not only a fundamental human right, but a necessary foundation for a peaceful, prosperous and sustainable world." However, although increasingly organizations are advancing women (as well as minorities) to senior level positions but only a limited number of functional areas, such as public relations and communications. This can be referred as? (A) Glass ceiling (B) Glass wall (C) Glass cabinet (D) Glass floor (E) Glass bamboo