The basic problem solving procedure works best when:

A) The leader is trained in the process
B) The group is large
C) The members are trained in the process.
D) ​Both the leader and the members are trained in the process.

The basic problem solving procedure works best when both the leader and the members are trained in the process. This ensures that everyone involved understands the steps and can effectively contribute to the solution. A large group can make the process more difficult and may not be necessary for all problems.