Although the final version of the contract has yet to be completed, an overview of the revisions

that the parties have agreed upon _______ by the lawyer.

a) being provided   b) are provided   c) has been provided    d) provide

위 문제에서  that the parties have agreed 의 that 이 형용사절 인지요.  upon 은 어떻게 해석해야 하나요?