What is the maximum speed you cannot exceed when driving an adaptable mixed vehicle on a motorway?

Why this is the correct answer

An "adaptable mixed vehicle" (in Spanish: "vehículo mixto adaptable") is a vehicle specially designed to serve two purposes: carrying passengers AND carrying goods. Its key feature is that the interior can be reconfigured — seats can be added or removed — so the same vehicle can switch between transporting people and transporting cargo. It can carry up to 9 people including the driver. Common examples include commercial vans like the Citroën Berlingo or Peugeot Partner when registered for dual use (code 3100 on the vehicle's technical sheet, versus code 1000 for a standard passenger car). Because of this dual-use classification, Spanish traffic rules impose lower speed limits on these vehicles compared to regular passenger cars (turismos). The speed limits for an adaptable mixed vehicle are: motorways and dual carriageways — 100 km/h (vs. 120 km/h for a regular car); conventional roads with a hard shoulder of at least 1.5 m or more than one lane per direction — 90 km/h; other conventional roads — 80 km/h. The correct answer is C) 100 km/h.