下列文件中通常属于音频文件的是（）。

A.musiC.txt

B.musiC.miD

C.musiC.DoC

D.musiC.Bmp

Which of the following accounts for Andrew Carnegie’s success().

A.His ability to sell the product and his policy of expanding business.

B.His reputation as the King of steel.

C.His founding of the steel industry in the United States.

D.His creation of a global distribution network.