Choose the word or phrase among A, B, C or D that best fits the blank space following passage.Opportunities for communication and collaboration have also been expanded by technology. Traditionally, classrooms have been relatively isolated, and collaboration has been limited to other students in the same (31) _______ or building. Today, technology enables forms of communication and collaboration undreamt of (32) ________the past.Students in a classroom in the rural U.S., for example, can learn about the Arctic by following the expedition of a team of scientists in the region, read scientists’ blog posting, view photos, e-mail questions to the scientists, and even talk (33) _________with the scientists via a videoconference. Students can share what they are learning with students in other classrooms in other states (34) ________are tracking the same expedition. Students can collaborate on group projects using technology-based tools such as wikis and Google docs. The walls of the classrooms are no longer a (35) ________as technology enables new ways of learning, communicating, and working collaboratively.