Question

complete the sentence with the correct plural.
the \boxed{} will go through a rigorous safety instruction program before they can use the complicated machinery unsupervised.
(employee - in - training)

Explanation:

To form the plural of the compound noun "employee-in-training", we add the plural marker to the main noun (the head of the compound, which is "employee") while keeping the rest of the structure intact.

Answer:

employees-in-training