Answer: Option (d) is the correct answer.
Step-by-step explanation:
Metals are the species which contain more number of electrons.
When a specie loses electrons then it acquires a positive charge. Whereas when an atom gains electrons then it acquires a negative charge.
Thus, as metals have more number of electrons, therefore, in order to gain stability metals readily lose electrons.
Hence, metals naturally form positive ions, by losing electrons to empty the valence shell.