Final answer:
To fix the price of oil for delivery in 3 months, an oil refiner should use a crude oil futures contract, which facilitates buying oil at a predetermined price, safeguarding against potential price increases or market shifts.
Step-by-step explanation:
The question pertains to a strategy that an oil refiner can employ to fix the price they will pay for oil in 3 months. In this scenario, where an oil refiner would like to lock in a future purchase price, the most appropriate derivative strategy would be to use a crude oil futures contract. This type of contract will obligate the refiner to purchase a specified amount of oil at a predetermined price on a future date. The crude oil futures contract provides certainty regarding the future cost, which can be advantageous if, for example, the price of oil rises or if there are shifts in the supply curve, such as those experienced during historical events like the 1973 OPEC oil embargo.