Why are high-decker touring coaches and double-decker buses particularly vulnerable to strong crosswinds (Seitenwind)?

1. Because their dual rear tyres have less road contact than single tyres
2. Because they present a large lateral surface area (große Angriffsfläche) and have a higher centre of gravity
3. Because compressed air suspension collapses automatically in high wind
4. Because diesel fuel sloshes back and forth inside the tank