asset class Prescription {…}

interface Pharmacy {
  void depositPrescription(owned Prescription >> unowned Prescription p);  
  owned Prescription removePrescription(unowned Prescription p);
  unowned Prescription getAnyPrescription();
}
 
class Patient {
  void fillPrescription(unowned Pharmacy pharmacy, unowned Prescription pre) {
    pharmacy.depositPrescription(pre); // Location (A)    
    
    Prescription pre2 = pharmacy.getAnyPrescription(); [pre2 unowned];
    Prescription removedPrescription = pharmacy.removePrescription(pre2); [removedPrescription owned]; // Location (B)
    pharmacy.depositPrescription(removedPrescription); [removedPrescription unowned]; // Location (C)
  }
}

For each location where the compiler will give an error, check the corresponding box and explain why there is an error.