Isabella's principal residence is located in Bismarck, North Dakota. She purchased it for $400,000 in 2019 with a $40,000 down payment. The remaining balance was financed with a mortgage loan. In 2023 , the house is worth $500,000 with a mortgage balance of $300,000. Due to an unforeseen economic hardship, Isabella obtained a second mortgage on the home in the amount of $100,000. She used the proceeds to pay off her high-balance credit cards and purchase a new car. How much can Isabella deduct as mortgage interest expense on her 2023 tax return if the interest payment on the first loan is $15,000 and the second one is $5,000 ? A) $0 B) $20,000 C) $15,000 D) $5,000