The correct answer to the question is Rubidium (Rb)
Rubidium (Rb) is a group 1 element and as such, it can form bond by losing it's valence electron (i.e 1 electron) easily.
Gallium (Ga) is a group 13 element. It can only form bond by losing it's 3 valence electrons.
Argon is a group 18 element. This group has completely filled outermost shell and are very stable. They do not involve in bond formation.
Iodine (I) is a group 17 element. It is more difficult for this group to lose its 7 valence electrons hence, they form bond by accepting 1 electron.
With the above information, we can conclude that Rubidium will most likely lose electron to form bond.
Learn more: https://brainly.com/question/13178080