Sorry but I think this question is a bit wrong as an element contains lots of atoms more than 2 atleast, if this is a question from your textbook or test etc, then perhaps C is the better option.
Remember:
1 atom doesn’t make an element, 2 or more different types of atoms make an element but one thing, Golds symbol is AU, hmm I think the answer would be 2 or 3 while AU seems to be an abbreviation of gold (symbol in science) from a Latin word. But I hope this helps, I guesss I was confused above
