题目

Most Americans get what money they have from their work; that is, they earn an income from wages or salaries. The richest Americans, however, get most of their money from what they own — their stocks, bonds, real estate, and other forms of property, or wealth. Although there are few accurate statistics to go by, wealth in American society appears to be concentrated in very few hands. More than 20 percent of everything that can be privately owned is held by less than one percent of the adult population and more than 75 percent of all wealth is owned by 20 percent of American adults. The plain已知向量，满足，且，，则与的夹角为（ ） A. B. C. D.