Is the supply of copper-rich ores greater or lesser than iron-rich ores?

Hi! I am not sure it is a Guess but I think it is lesser if I am wrong pls let me know.

We know that the mass number (top number) must be 33 because the electron that is emitted has no mass. The atomic number (bottom number) must be 15, because it is one less than 16 and the electron has a negative charge. Therefore, the first box is the answer.