A unit propelled by any form of energy or a combination of units operated from a single control, used in road or yard service.

• A. Track Car
• B. Multiple Unit Equipment
• C. Engine (ENG)
• D. Block Signal System

Answer: (C)

The propulsion unit that moves trains, whether a single power unit or a group of units tied together, and controlled from one cab, is what this item is describing. An engine (locomotive) is the power source for road or yard movements, and it can be powered by any form of energy—steam, diesel-electric, electric, or even a set of locomotives working in concert under one operator. In yard work, you’ll see engines shunting cars and assembling or breaking apart consists, all controlled from a central cab, which fits the description precisely.

Track cars are generally light maintenance vehicles used on the rails, not the primary motive power for moving trains. Multiple Unit Equipment refers to self-propelled cars that form a train and are driven from a single control, typically for passenger service; while they can be commanded from one control, the item here emphasizes the main power unit used to pull or haul in road or yard service, which is the engine.