Astronomers analyze starlight to determine a star's (a) temperature; (b) composition; (c) motion; (d) all of the above.

One of the characteristics of the luminous gas clouds is that they do not have direct affectation by some type of external electric or magnetic fields.

In addition, we must bear in mind that color is a variable that is depending on the gas in the mixture. Therefore its relationship with spectroscopy allows us to deduce that scientists take advantage of the wavelength spectrum to know the type of composition of one of the clouds. The speed of a cloud is measured by determining the Doppler shift of its spectral lines. From wine's law, wavelength of light emitting from the object depends on temperature of object

Therefore the correct option is D