Draw a correct Lewis structure for [C2O4]2- and include the formal charges.
a. O-C(=O)-C(=O)-O with formal charges on each oxygen of -1 and formal charge on each carbon of +1
b. O-C(=O)-O-C(=O)-O with formal charges on each oxygen of -1 and formal charge on each carbon of +1
c. O=C-O-C(=O)-O with formal charges on the leftmost oxygen of -1, formal charge on the carbon of +1, and formal charge on the rightmost oxygen of -1
d. O=C-O-C(=O)-O with formal charges on the leftmost oxygen of -1, formal charge on the carbon of +1, and formal charge on the rightmost oxygen of -1