What does a circular white sign with a red border containing two cars side-by-side (the left vehicle depicted as a red truck, the right vehicle depicted as a black car) indicate?

1. Overtaking prohibited for heavy goods vehicles (Proibição de Ultrapassar para Automóveis Pesados / C14b)
2. Trucks must overtake on the right only
3. Designated lane for heavy freight transport
4. Two-way truck traffic ahead