Answer:
D. Person who buys vacant land hoping its value will increase
Explanation:
A speculator is basically someone who takes a chance on losing a lot of money when there's a prospect of making even more money. A speculator might, for example, invest in a risky stock in the hopes she can sell it eventually at a profit. Since the person was taking a chance on whether the land would increase in value (so he/she could make a profit) or decrease in value (and he/she would lose money), it makes he/she a speculator.