On October 1, Denise exchanged an apartment building (adjusted basis of $575,000 and subject to a mortgage of $325,000) for another apartment building owned by Quinn (fair market value of $850,000 and subject to a mortgage of $325,000). The property transfers were made subject to the outstanding mortgages. What amount of gain should Denise recognize?

a. $0.

b. $50,000.

c. None of the above.

d. $225,000.

e. $275,000.