How would Sam's response to Bruce's offer be classified when he changed the closing date?

Sam's response to Bruce's offer would be classified as a counter offer because altering a significant term of the original offer, such as the closing date, indicates that Sam is not accepting the offer as it stands. Instead, by suggesting a new closing date, Sam is proposing a modification to the terms of the deal. This action effectively nullifies the original offer and creates a new one that Bruce would need to accept for the negotiation to continue.

In real estate transactions, a counter offer demonstrates that one party is willing to negotiate but under different terms. Once a counter offer is made, the original offer is considered rejected, and the negotiation process starts anew based on the terms of the counter offer.