At Present, What Is the Primary Way That Astronomers Carry

Multiple Choice

At present, what is the primary way that astronomers carry out SETI programs (that is, search for extraterrestrial intelligence) ?

A) by using radio telescopes to search for signals from extraterrestrial civilizations
B) by analyzing high- resolution images of nearby stars in search artificial structures
C) by analyzing the spectra of extra- solar planets in an attempt to detect oxygen
D) by searching for planets around distant stars
E) by using X- ray telescopes to search for signals from extraterrestrial civilizations