Answer:
Unilateral contract
Explanation:
A unilateral contract is one which is agreed to based on the performance of one party.
Simply put, a unilateral contract in one in which there is agreement based on performance.
From the above question, the carpenters performance determines the contract. If he fixes the job within Saturday, he gets $1,000. If he doesn't finish within saturday, the carpenter doesn't get $1,000. The 'saturday' is the conditon for the payment of $1,000.