Final answer:
The train operator was most likely sent for examination to prevent the introduction of contagious diseases to the country through immigration.
Step-by-step explanation:
The most probable reason for sending the train operator to have an examination was to prevent the introduction of contagious diseases to the country through immigration. In the late 19th and early 20th centuries, immigrants arriving in the United States went through various medical examinations at Ellis Island to check for diseases, such as trachoma, which required having one's eyelids inverted. These examinations were aimed at protecting public health and preventing the spread of contagious diseases.