对开发我国东北地区做出贡献的少数民族首领是[ ]

A．大祚荣

B．皮罗阁

C．元昊

D．骨力裴罗

According to the passage, if one wants to predict the way consumers will spend their money, he should_____.

A．rely on traditional assumptions about earning and spending

B．try to encourage or discourage consumers to spend money

C．carry out investigations on consumer behavior and obtain data on consumers' incomes and money spending motives

D．do researches in consumer psychology in a laboratory