【单选题】According to the passage, in the Cepheid variable method all of the following have a significant role in the calculation of the distance of a galaxy EXCEPT
A.
The intrinsic luminosity of a Cepheid
B.
The comparative luminosity of ordinary stars
C.
The observed brightness of the Cepheid
D.
The data suggesting the expansion of the universe
E.
The correction of the period-luminosity relation for the star being observed