The correct answer is C. Both A and B.
A contract of sale of goods is an agreement between two parties, the seller and the buyer, for the transfer of ownership of goods from the seller to the buyer in exchange for a price. The agreement must be made for a specific good or goods, and the price must be agreed upon by both parties.
A sale is the transfer of ownership of goods from the seller to the buyer in exchange for a price. The buyer must pay the price, and the seller must deliver the goods.
An agreement to sell is an agreement between two parties to sell goods in the future. The agreement must be made for a specific good or goods, and the price must be agreed upon by both parties. However, the buyer does not have to pay the price, and the seller does not have to deliver the goods, until the agreement is completed.
In conclusion, a contract of sale of goods includes both a sale and an agreement to sell.