Final answer:
A trainer should consider the trainee's language skills when selecting an instructional method, as it is critical for effective communication and understanding of the materials.
Step-by-step explanation:
When considering the instructional method to use, a trainer should consider the factor Trainee's Language Skills. This is crucial in ensuring effective communication and understanding of the instructional material. Factors such as the trainee's age can also play a role depending on the context, but language skills are fundamental for a trainee to follow the materials being presented. Unlike factors such as height or birthplace, language skills directly impact a trainee's ability to receive and process information provided during training sessions.