Answer:
3) Unrealized Gain on Trading Investments of $1,500.
Explanation:
By January 1, Bargain Company had recognized a $18,500 gain on their investment (the valuation allowance account had a debit balance = gain). By the end of the year, the gain on the investment had increased to $20,000 (= $100,000 - $80,000), so you need to recognize an additional gain of $1,500 (= $20,000 - $18,500).