Who may enter a street that has this sign?

The sign "Fahrradstraße" indicates a bicycle street where cyclists have priority and the primary use is for bicycles. Other vehicles are generally not allowed to enter unless specifically permitted. The additional sign "Anlieger frei" means "residents and persons with a legitimate reason (such as visitors to residents or deliveries) are allowed to enter."

Therefore, all cyclists can enter freely since the street is primarily for bicycles. In addition, persons visiting residents ("Anlieger") are allowed access despite not being cyclists. Moped riders, however, are not allowed to enter unless they fall under the "Anlieger" category, which generally they do not by default.

This is why only options 1 (all cyclists) and 2 (all persons visiting residents) are correct according to German traffic rules for this street sign combination.