Identify a true statement about quasars.
A) Their spectra are similar to the spectra of stars.
B) Their spectra do not show any redshift.
C) They exhibit fluctuations in their brightness over time scales of hours or minutes.
D) They are supermassive structures with a diameter of 20 to 50 Mpc.
Question 2
The brilliant nuclei of Seyfert galaxies change brightness rapidly, in only a few hours or minutes, especially at _____.
A) microwave wavelengths
B) visible light wavelengths
C) gamma ray wavelengths
D) X-ray wavelengths