During the tax year, Leland sold an office building that he had owned and rented to the same tenant for 16 years. The building had been depreciated using regular MACRS. Leland sold the building at a gain. On which part of Form 4797 is the sale of the building first reported, and what IRC section determines the type of gain?

Part I, Section 1231.

Part II, Section 1231.

Part III, Section 1245.

Part III, Section 1250.