Final answer:
Wilbur's house served as a store of value between 2003 and 2006 because it retained and increased its worth over time. It did not serve as a medium of exchange or a unit of account during this period. The correct option is C. store of value.
Step-by-step explanation:
Wilbur's house served as a store of value during the time he owned it. When Wilbur purchased his house for $175,000 in 2003 and later sold it for $325,000 in 2006, the house retained and increased in value, making it an asset that preserved its worth over time. This concept is important in the economy because, to act as a store of value, an asset must maintain its value over time so it can be used in the future without a significant loss of worth.
In contrast to a store of value, a medium of exchange is used to facilitate the buying and selling of goods and services, whereas a unit of account provides a common measure of value. Since the house was not used to buy or sell goods and services directly, nor was it employed to measure the value of other items, the correct answer to Wilbur's situation is clear. Therefore, the house did not serve as a medium of exchange or unit of account. In essence, the house was much like holding money in that it could be kept for future use without greatly diminishing in value, which is in stark contrast to, for example, perishable goods.