Final answer:
The question regarding the number of classes of powered industrial trucks the Industrial Truck Association has classified them into cannot be answered with the provided information, which focuses on worker preferences rather than industry classifications.
Step-by-step explanation:
The Industrial Truck Association categorizes powered industrial trucks into several classes. While the data provided above includes interesting information about the preferences of different groups of workers towards trucks, it does not specifically answer how many classes of powered industrial trucks exist according to the Industrial Truck Association.
To answer the question accurately, one would instead refer to industry standards that classify powered industrial trucks into classes based on their features and uses. Typically, there are multiple classes ranging from electric motor rider trucks to internal combustion engine trucks, each designed for different applications within warehouses, manufacturing plants, and other industrial environments.