An astronomer identifies the wavelength corresponding to the peak

An astronomer identifies the wavelength corresponding to the peak intensity of radiation from a star. From applying Wien's law she would know the star’s -----. If she also knew the star’s radius, she could use the Stefan-Boltzmann law to get its ---.
a. luminosity, temperature
b. temperature, chemical potential
c. luminosity, mass
d. temperature, luminosity (Answer)
e. mass, luminosity

peak