Type Ia Supernovae Are Frequently Used as Standard Candles for the Measurement

Type Ia supernovae are frequently used as standard candles for the measurement of distances to galaxies, but they are not all equally luminous. What additional relationship between properties of supernovae is used to determine specific luminosities for individual supernovae?

A) the more blue the spectrum of the supernova, the more luminous the supernova
B) the faster the rise of light intensity during the explosion, the more luminous the supernova
C) the slower the decay of intensity after the explosion, the more luminous the supernova
D) the faster the decay of intensity after the explosion, the more luminous the supernova