The Technique Called Photometry in Stellar Astronomy Is the Measurement

The technique called photometry in stellar astronomy is the measurement of the

A) arrival times of photons from variable and pulsating stars to determine accurately the pulsation or rotation periods of these stars.
B) intensity of light from stars through several limited-bandpass filters from which surface temperature, variability, luminosity, and so on of stars can be determined.
C) relative absorption of light by different atoms and molecules in high-resolution spectra of starlight, from which stellar temperatures can be estimated.
D) precise positions and relative motions of stars in the Galaxy, from which galactic structure and overall rotation can be determined.