Use reasoning to lead to the answer of the following question:
The piece of paper was worth a lot of money, it was an old Apple Inc what?\nOptions:\n- notebook\n- copy machine\n- stock certificate\n- ream\n- thumb drive
 Reasoning process:
User
Stock certificates have a lot of money as they are used for trading. Apple Inc can have stock papers which have a lot of value as they company is valueable. Therefore, the final answer is stock certificate.
Assistant