Before two parties enter into an OD relationship, it is recommended that they are in involved in which of the following?

a$.$ Clarification of how the change will be evaluated at the end of the project.

b$.$ Discussion of the changes that need to be made.

c$.$ Clarification of the nature of the organization's current functioning and the issue$($s$)$ to be addressed.

d$.$ Discussion of the OD professionals who need to be hired.