Which of the following statements about tank vehicles is true?

Tank vehicles indeed require special skills to haul liquid tanks due to the unique challenges presented by the liquid cargo. When a tank vehicle is in motion, the liquid inside can shift, causing the vehicle to sway or become unstable. This phenomenon, known as "sloshing," can affect the driver's ability to control the vehicle, especially during turns, stops, or sudden maneuvers. Proper training and experience are necessary to handle these dynamics safely, making the statement about needing special skills accurate.

The other options misrepresent the characteristics of tank vehicles. For example, tank vehicles can be more complicated to drive compared to standard vehicles due to the shifting weight of the liquid. They also do require special handling during loading, transport, and unloading to ensure safety and compliance with regulations. Lastly, tank vehicles can vary greatly in weight; they are not always lighter than other vehicles, as their loads can range from very light to quite heavy depending on the liquid being transported and the vehicle's design.