单选题 An analyst does research about Bollinger Bands. With respect to technical anaIysis indicators, Bollinger Bands depict a set number of standard deviations from:
A. average return.
B. average price.
C. average volume.

【正确答案】 B
【答案解析】[解析] 布林线(Bollinger Bands)是由平均价格加上或减去几个标准差而画成的。