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A
The tank will crack from road vibration
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B
High center of gravity combined with liquid surge can cause the vehicle to roll over, especially in partially filled tanks where free liquid movement generates lateral forces in the turn
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C
Tank vents may open and spill cargo
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D
Steering becomes lighter in curves
Why this is the answer
Tanker rollover is the most common serious tanker accident type and is directly caused by the interaction of two factors: HIGH CENTER OF GRAVITY — liquid tankers have a much higher center of gravity than dry freight because all the weight is in a single cylindrical container high above the axles; LIQUID MOVEMENT — when a partially filled tank goes into a curve, the liquid can shift toward the outside of the turn, adding lateral momentum that makes rollover more likely than with a solid load of the same weight. CRITICAL NUMBERS: A tank that is 80% full or less is more dangerous than one that is completely full, because the liquid has room to surge; a full tank moves as a single unit, a partially filled tank allows the liquid to amplify the destabilizing forces; the worst fill level is typically 50-70%. SAFE DRIVING ADJUSTMENTS: Reduce speed significantly before entering curves — do not wait until you are in the curve to brake; take curves at well below the posted advisory speed (those speeds are for standard vehicles, not high-CG tankers); know your vehicle's specific center-of-gravity characteristics; never trust that your speed 'feels' safe — rollover happens suddenly without warning signs.
Source: FMCSA CDL Manual, Chapter 10, Tank Vehicles, High Center of Gravity