Which of the following statements about Cepheid variable stars are correct?

A、Cepheid variable stars, also known as long-period Cepheid variable stars or classic Cepheid variable stars, are a type of pulsating variable star.;

B、The brightness of such variable stars changes periodically.;

C、The luminosity of such variable stars varies between 0.1 and 2.0.;

D、According to a large number of studies on Cepheid variable stars, the longer the period of Cepheid variable stars, the smaller the average luminosity.;

E、Cepheid variable stars are often hailed as "gauges".