With regard to consideration in a sales contract, the UCC differs from the common law in that: A) terms of a sales contract may be modified without additional consideration.
B) consideration is not required in sales contracts
C) terms in a sales contract may be modified as long as additional consideration is provided.
D) consideration exchanged must be equal or very closely equal in sales contracts.

A) terms of a sales contract may be modified without additional consideration.

Explanation:

Generally speaking, common law applies to everybody in an equal manner, i.e. the law is the same for everyone. While UCC rules vary depending if the parties involved are merchants or not. UCC has two standards, one that applies to merchants and another one that applies to everyone else.

Common law applies to all contracts that are not covered by UCC rules. UCC rules only apply to the sale of goods and this doesn't include money or securities. Under UCC rules, new consideration is not a requirement to modify an existing contract. E.g. a buyer places an order for 3,000 units, but the seller only has 2,000 units available. The seller can send the 2,000 units and if the buyer accepts them, a new contract is formed.