Final answer:
The best question to measure the success of training aimed at increasing employee smiling in front of customers is A. Is there a change in performance observed in the participant after the training session? as it aligns with behavioral measurements and direct observations post-training.
Step-by-step explanation:
To measure the success of the service excellence training in terms of changing employee behavior to smile more in front of customers, the best question would align with behavioral measurements outlined in a study by Arthur et al. (2003). The correct choice is A. Is there a change in performance observed in the participant after the training session?
This choice directly assesses changes in behavior, which is the primary focus of the training, as opposed to the other options that measure learning outcomes, participant opinions, or indirect results, such as customer complaints. Measuring changes in performance can be done through observations and assessments by supervisors post-training, ensuring the intended customer service behaviors are being practiced.