What does a circular white regulatory sign with a red border depicting an exclamation mark and the text 'ALTURA MÁXIMA 4.2m' indicate to a machine operator transporting an excavator on a trailer?

1. Minimum height required to jump the bridge
2. Maximum vertical clearance limit of 4.2 meters; vehicles or loads exceeding 4.2 meters in total height are prohibited from passing under the structure (e.g. overpass, tunnel, or power lines)
3. Height of the trees in the area
4. Radio broadcast tower height