I can hear the backup generator from the courtyard.✓Respuesta correcta
Sam is knowing the access code now.
This bicycle is belonging to the new caretaker.
I am hearing the backup generator from the courtyard.
Explicación
The generator sentence is correct because involuntary perception at the present moment is naturally expressed with the modal can plus the perception verb. The closest distractor puts passive hearing into the continuous, a form standard English normally avoids.