The contract law concept of mitigation applies to which of the following circumstances?

A. a tenant's offer to surrender the premises that is accepted by the landlord.

B. a tenant's abandonment to which the landlord responds by re-entering and re-letting the premises on behalf of the landlord.

C. a tenant's abandonment to which the landlord responds by re-entering and re-letting the premises on behalf of the tenant.

D. to b. and c., but not to a.