On January 1, 2013, Randolph signed a two year lease to rent office space from Zoff. The lease commenced immediately on January 1, 2013. During 2013, Randolph paid Zoff, $36,000 for the first year's rent, $3,000 for the last month's rent, and $3,000 as a security deposit. Randolph and Zoff agree that the security deposit will be returned by Zoff at the end of the lease. How much gross income should Zoff report for 2013 as a result of these items?
a. $36,000
b. $39,000
c. $42,000
d. $144,000