A sole proprietor of a farm implement store sold a truck for $15,000 that had been used to make service calls. The truck cost $30,000 three years ago, and $21,360 depreciation was taken. What is the appropriate classification of the $6,360 gain for tax purposes?

a. Section 1231 gain.

b. Long-term capital gain.

c. Ordinary gain.

d. Short-term capital gain.