Troy, a cash basis taxpayer, owns an office building. His records reflect the following for 20X1. On March 1, 20X1, office B was leased for twelve months for $12,000. A $900 security deposit was received which will be used as the last month's rent. On September 30, 20X1, the tenant in office A paid Troy $3,600 to cancel the lease expiring on March 31, 20X1. The lease of the tenant in office C expired on December 31, 20X1, and the tenant left improvements valued at $1,400. The improvements were not in lieu of any required rent. Considering just these four amounts, what amount must Troy include in rental income on his income tax return for 20X1?

a. $17,900

b. $17,000

c. $16,500

d. $13,800