Final answer:
The extraordinary loss would reduce the value of the investment on the investor's balance sheet when using the equity method.
Step-by-step explanation:
If an investee company incurs an extraordinary loss and the investor is using the equity method to account for its investment, the correct statement is that the extraordinary loss would reduce the value of the investment. Under the equity method, investors recognize their share of the profits and losses from the investee in their own income statement. Therefore, any extraordinary loss reported by the investee reduces the investor's share of investee's income, and consequently the carrying value of the investment on the investor's balance sheet decreases.