【名词&注释】
半导体激光器(semiconductor laser)、发光二极管、根本途径(basic way)、电信号(electrical signal)
[单选题]Nobody had predicted the scale of impact of ( ) communications and that it world be one of the largest businesses in the history of mankind with and immense impact on all economies.[1分]
A. microwave
B. satellite
C. cell
D. cellular