Because it can lose or gain an electron. For example, it becomes a part of a molecule because it can form bonds
It looks like it would be the 1st answer choice...
Hope this helps!! (:
Answer:
Cardiovascular is the correct option
Group 7A, the Halogens contain metalloids such as Astatine.
Atom
Molecule
Organelle
Cell
Tissue
Organ
Organ system
Organism
