Sending Signals at Optical Wavelengths Might Be a Viable Alternative

Multiple Choice

Sending signals at optical wavelengths might be a viable alternative to radio wavelengths

A) only between civilizations around solar-type stars whose eyes have evolved to see such radiation
B) over relatively short distances where absorption by interstellar matter would not be a problem
C) as long as the light transmitted is a different color than the light given off by the parent star
D) over all distances as long as the intensity of the signal is strong enough