Brainiest if answered in the next 5m.

all atoms that react

have a full octet of electrons in their valence shell
do so to share, gain, or lose electrons to become stable
can be separated again through physical means
lose electrons

Atoms react because they wish to become a Noble Gas, and they do this by sharing, gaining, or losing electrons to become stable. The correct answer therefore is, "do so to share, gain, or lose electrons to become stable". Not all atoms have a full octet of electrons in their valence shell, this is dependent based on what type and how it's obtained. They can't be separated again through "physical" means and the claim "all atoms lose electrons" is invalid.