If a Galaxy Has a Recessional Velocity of 50,000 Km/s $\alpha$

Multiple Choice

If a galaxy has a recessional velocity of 50,000 km/s, at what wavelength will you observe the H $\alpha$ emission line? Note that the rest wavelength of the H $\alpha$ emission line is 656.3 nm.

A) 695.7 nm
B) 719.4 nm
C) 742.3 nm
D) 766.0 nm
E) 1750 nm