How Do Speculators Mitigate Shortfalls in the Equilibrium Quantities Traded

Multiple Choice

How do speculators mitigate shortfalls in the equilibrium quantities traded in markets?

A) by buying up unsold inventories and then selling them when there is a shortage in the market
B) by causing market quantities to rise and fall
C) by buying up items when the prices have risen
D) by buying up items in advance of rising prices, and then selling them in the market when prices increase