The word that refers to any system that uses an exchange medium - whether it is a precious metal or government-printed paper and that can be traded for other good is money. The answer to your question is choice or letter B.
It is important to form this type of group because each person has a different set of skills which helps to do things more efficiently and effectively. It also helps the group have a good sense of teamwork.
Reading a single review of a movie can be informative, but reading a synthesis of many reviews of the same movie can be much more informative about the effect the movie had across many individuals. This notion is analogous to the research strategy known as meta- analysis.
