It can become an ion because it can lose or gain an electron. It can become a part of molecule because it can form covalent bond with other atoms to gain a full valence shell.
I believe that the answer is A, if I am not mistaken!
This is because the shoulder has a shallower joint socket, so it can become dislocated easier.
Answer:proton
For our purposes at this point in the text, we can define an acid. as a substance with at least one hydrogen atom that can dissociate to form an anion and an H + ion (a proton) in aqueous solution, thereby forming an acidic solution.
Explanation: hope it helps!