Francisco Sells a Parcel of Land for $100,000 Cash and the Buyer

Francisco sells a parcel of land for $100,000 cash and the buyer also assumes Francisco's liability of $10,000.The basis of his land is $70,000.What is the gain or loss realized on the sale?

A) $10,000 gain.
B) $20,000 gain.
C) $30,000 gain.
D) $40,000 gain.