Answer: Scarcity reduced the supply of ivory.
Step-by-step explanation:
When a good is said to be scarce it means that the good is not widely available because the supply of the good is limited. Scarcity of ivory therefore reduced the supply of ivory.
Another main effect of scarcity of a good is that the good becomes more expensive. With the supply of a good becoming limited, there will not be a enough for people who want them so the prices will rise as people try to acquire it by paying more than others can afford.