What is vestibule training similar to?

Explanation of correct option :

Vestibule training is similar to on-the-job training because the learning takes place at the worksite emergency.
The difference between vestibule training and on-the-job training is that in vestibule training, the employees are trained with mock equipment rather than actual equipment.
This means that the trainees can learn to operate machines without fear of breaking them or causing injury to themselves or others.

Explanation of incorrect option :

Off-the-job training is not as practical as vestibule training because it does not use the actual place or places where you will be working.  
Refresher training is when a person has trained again after some time has passed, usually because of changes in regulations or technology.  
Apprenticeship training gives at the same time learning theory and skills in a classroom setting. It's more hands-on than vestibule training.

Final answer:
Hence, the correct option is A. On-the-job training.