What Is the Difference Between a Type I Cepheid $\delta$ Cepheid Star) and a Type II Cepheid?
A) Type I

What is the difference between a Type I Cepheid ( $\delta$ Cepheid star) and a Type II Cepheid?

A) Type I Cepheids are main-sequence stars, while Type II Cepheids are giant stars.
B) Type I Cepheids are short-period variables, while Type II Cepheids are long-period variables.
C) Only Type I Cepheids have a simple relationship between luminosity and period.
D) Type I Cepheids are brighter metal-rich stars, while Type II Cepheids are dimmer metal-poor stars.