In populated areas, stopping and parking on the left side of a one-way road are allowed. The exception is trucks heavier than 3.5 tonnes, which may only stop; buses may also park.
Under the Rules, in populated areas stopping and parking on the left side of one-way roads are generally allowed (clause 79). The restriction to stopping only — for loading or unloading, or for a passenger to get in or out — applies only to trucks with a maximum permissible weight over 3.5 tonnes, not to buses.
Option 2. There is no rule that prohibits buses from stopping and parking on the left side of one-way roads in populated areas.
Option 3. The stopping-only restriction applies only to large trucks, while buses may also park.