________ is a method of commercial dealing that is commonly used in a particular field or industry.

A) Usage of trade
B) Contract for sale
C) Good faith
D) Firm offer

Usage of trade refers to common practices and customs that are widely accepted and expected within a specific industry or field. It is often used as a basis for determining whether a party has acted in good faith or breached a contract within that particular industry. Contract for sale, good faith, and firm offer are all related terms, but do not specifically refer to a commonly accepted method of commercial dealing.