Abby sold a parcel of land for $18,000. She paid a real estate agent a commission of $1,200 for assisting with the sale. Abby had purchased the land several years earlier for $14,500. What is the gain on the sale of the land?
a. Gain of $3,500
b. Gain of $16,800
c. Gain of $18,000
d. Gain of $2,300