Use 2018 tax rates. Show work please

21. John bought a primary residence in 2010 for $250,000. January 1, 201 house can they exclude? Mary, his girlfriend, moved in with him on 6 when the house was worth $300,000. They got married on June 15, 2017 when the was worth $400,000. They sold the house on January 2, 2018 $800,000. How much of their gain a. $250,.000 b. $500,000 C. None of the gain d. All of the gain. None of the gain is taxable .e. $400,000