A surcharge is an additional premium applied when the insurer identifies a higher-than-standard risk characteristic. The purchase of a new sports car for a teenage son to drive is the clearest surcharge trigger because it combines two rating concerns: a high-performance vehicle and an inexperienced or youthful driver. This increases both claim frequency and claim severity potential. A teenage driver may attract higher rates due to limited driving experience, while a sports car typically has higher repair costs, theft exposure, and accident potential. Option A may affect underwriting interest or mortgagee information, but simply having two mortgages does not normally create a surcharge in the same direct way. Option B would usually improve the risk and may qualify for a discount, not a surcharge. Option C may reduce risk or fall into ordinary vehicle substitution rating, depending on the vehicle, but it is not the strongest surcharge indicator. The technical principle is that rating adjustments follow measurable risk characteristics. References/topics: From Quote to Policy; rating factors, surcharges, automobile underwriting, youthful operators, vehicle classification.