声音的产生与传播中，下列说法错误的是（　　）

A．声是由物体的振动产生的

B．频率小于2000Hz的声音人们都能听到

C．声音传播需要介质

D．噪声是发声体做无规则振动时发出的声音

During the 1920s in Germany and during the 1980s in Brazil and Israel, inflation reached hyperinflationary levels. People received their wages and spent them immediately. Companies received revenues from their sales and immediately paid them out as wages and dividends. This behavior best reflects which one of the following adverse effects of inflation for an economy（）

A. Tax distortion.

B. Gains by employers at the expense of employees.

C. Increased transactions costs.