please explain

Margie has a country retreat that she uses as a vacation home. She also owns a house in the city that is her principal residence. She acquired the country property many years ago for $130,000; it is now worth $540,000. She is concerned the property will continue to appreciate in value and the eventual tax liability that will be triggered on death could erode her estate. She wants the property to go to her son, Conner. Margie has decided to sell her vacation home to Conner immediately for its fair market value. However, she told Conner he could pay her in equal annual installments of $180,000 with the first installment payable at the time of sale. How much can Margie claim as a capital gains reserve for this year? a) $273,333 b) $328,000 c) $360,000 d) $410,000