What does adding a pre$-$measure do to a post$-$measure training evaluation design?

Adding a pre$-$measure tells you if the training was cost effective.

Adding a pre$-$measure lets you determine what the skill level of trainees was prior to training.

Adding a pre$-$measure tells you whether the trainer had the skills to do the training.

Adding a pre$-$measure lets you know if the trainees were prepared for training.