In an observational study, what distinguishes a confounding variable from a lurking variable?

A confounding variable is always controlled for, while a lurking variable is always ignored

A confounding variable only affects the response variable, while a lurking variable only affects the explanatory variable

A confounding variable is measured or considered in the study, while a lurking variable is not included or measured

A confounding variable is unrelated to the explanatory variable, while a lurking variable is unrelated to the response variable