Answer:
Acceptance
Explanation:
For a contract there are some certain conditions to be fulfilled, to call it valid. This includes the basic two things:
Offer and acceptance.
Offer refers to the option provided by a party in the contract and that there is acceptance from opposite party to accept the offer, and when it is accepted as the offer itself, then the contract is valid.
In the given instance there is an alteration in the acceptance conditions as not same like offer. The offer price is $5,000 and that the acceptance price is $4,500.
Thus, there is no acceptance in this contract. Rather there is counter offer.