Under GB/T 22485-2021, what is the mandatory requirement regarding taxi vehicle exterior cleanliness, corporate logos, and authorized commercial advertisements?

1. The vehicle body must be washed clean, company emblems and pricing decals legible, and approved commercial advertisements must not obscure vehicle windows or safety signage
2. Commercial advertisements may be pasted across the entire front windshield as long as the driver wears glasses
3. Exterior vehicle paint may be covered with mud as long as the vehicle engine runs well
4. License plates can be partially obscured by advertising stickers