The right to drive buses of category βDβ and subcategory βD1β is given to persons who have reached 21 and already hold a βBβ, βCβ or βC1β license.
Under the Law βOn Ensuring Road Traffic Safetyβ (article 27), the right to drive category βDβ and subcategory βD1β vehicles is given only to persons who hold a driver's license for category βBβ or βCβ or subcategory βC1β and have reached 21 (19 if they have been conscripted into the armed forces and other troops). This ensures enough experience and maturity to drive passenger vehicles.
Option 2. 18 is not enough: the age set by law for categories βDβ and βD1β is 21 (19 for conscripts).
Option 3. Holding categories βABβ or subcategories βA1B1β and being 18 does not meet the 21-year threshold required to drive passenger vehicles.
Option 4. The age required to drive category βDβ and βD1β vehicles is 21 (19 for conscripts), not 20.