Hydrogen Gas Emits a Strong Spectral Line of Red Light $\alpha$

Multiple Choice

Hydrogen gas emits a strong spectral line of red light with a wavelength of 656.3 nm (the Balmer $\alpha$ line) . This emission line is seen in the spectrum of a distant quasar but at a wavelength of 721.9 nm. Applying Doppler's relationship, how fast is this object moving with respect to Earth, in terms of the velocity of light, c?

A) 1/10 c
B) 1.1 c
C) 1/100 c
D) 10 c