Answer:
The Correct answer would be an element with a high electronegativity and with a single valence electron.
Step-by-step explanation:
Atoms need 8 electrons in their outershells to be stable. If they don't have eight, they will try to borrow from other atoms. So if an atom only needs one more electron, think of it as being desperate and highly reactive. When an atom with only one valence electron (electron in the outershell) comes along, it's the easiest victim to borrow off of.
I hope this helps!! <3