In early 2013, Irma sold her personal residence to David for $300,000. At the time of the sale, Irma's adjusted basis was $50,000. Within three months of the sale, Irma moved into a new residence she purchased for $800,000. What is Irma's basis in her new residence?
a. $50,000
b. $250,000
c. $550,000
d. $800,000