Joseph and Sandra Williams, married taxpayers, took out a mortgage on their home for $350,000 15 years ago. In May of this year, when the home had a fair market value of $450,000 and they owed $250,000 on the mortgage, they took out a home equity loan for $220,000. They used the funds to purchase a single engine airplane to be used for recreational travel purposes. What is the maximum amount of this home equity debt on which they can deduct interest on an individual income tax return filed for the 2020 taxable year?

a. $ 0

b. $ 100,000

c. $ 220,000

d. $ 230,000

e. None of the above