The answer is bull.
A bull is a speculator who expects a rise in the price of securities in the future. They buy securities in the hope that their prices will increase, and they sell them when the prices have reached a level that they believe is profitable.
A bear is a speculator who expects a fall in the price of securities in the future. They sell securities in the hope that their prices will decrease, and they buy them back when the prices have reached a level that they believe is profitable.
A stag is a speculator who buys securities in the hope that they will be able to sell them at a profit to a company that is planning to go public.
A lame duck is a politician who is no longer in power and is not seeking re-election.
In the context of the question, the correct answer is bull because the speculator expects a rise in the price of securities in the future.