As the servicer of the mortgage loans, First National Bank is responsible for filing the mortgage interest information returns. This is because it collects the interest payments and maintains the necessary information regarding the loans and payments. Option C is incorrect because the responsibility for filing the information returns typically lies with the entity that collects the interest payments, regardless of whether they were the original owner of the loans. Options A and B are incorrect because, although the investors own the loans, First National Bank, as the servicer, is the entity responsible for managing the loans and handling the interest payments, making it responsible for filing the information returns.