Carol and Bob Enter into a Contract for Bob to Perform

Multiple Choice

Carol and Bob enter into a contract for Bob to perform waste management services for Carol's commercial properties. Later, Bob alters a material term-increases the price-without Carol's knowledge or consent. She​

A) ​can alter a material term, such as the payment date, without Bob's consent.
B) ​can treat the contract as discharged.
C) ​must adapt her performance accordingly.
D) ​must determine whether Bob's alteration constitutes substantial performance.