What role do Fraunhofer lines play in spectroscopy? Hawking's universe-1B (19. century astronomy- Assignment 4) Question 8 options: a) they carry information from stars on their speeds and distances (physical knowledge) but they don't say anything about the chemical composition of the source b) it is the phenomenon which explains the stretching and squashing sound waves from a moving source and therefore the change in its pitch, as in the example of the changes in sound of an ambulance as it passes by c) they are dark absorption lines in the spectrum of light, and they play important role by carrying information on chemical composition and physical properties of the source such as its speed and distance d) they are defining the Doppler effect in any types of waves including light waves, radio waves, water waves and soundwaves