The question asks 'Have you seen such a car before?' In German, 'so ein Auto' (such a car) becomes 'solche Autos' (such cars) in the plural. Option D correctly uses 'solche Autos' with proper word order. The other options incorrectly use 'jegliche' (any kind of), 'manche' (some), or 'welche' (which), which don't match the demonstrative meaning of 'so ein'.