A Certain Spectral Line of Hydrogen Has a Wavelength of 410.2

Multiple Choice

A certain spectral line of hydrogen has a wavelength of 410.2 nm when observed in the laboratory.If the same line appears in a star's spectrum at 410.0 nm,what can you conclude about the motion of the star?

A) The star is moving away from the observer.
B) The star is moving toward the observer.
C) The star is moving but the direction is not known.
D) The star is not moving toward or away from the observer.