What cannot be changed by a pharmacist on a prescription?

A pharmacist must adhere to strict regulations when handling prescriptions, especially concerning what information can and cannot be modified. The date of the prescription, the patient's name, and the medical practitioner’s signature are all critical elements that establish the validity and legality of the prescription.

Modifying the date of the prescription could result in confusion regarding the timing of therapy and could potentially lead to prescriptions being deemed invalid if they are filled too early. The patient's name is fundamental for ensuring that the right individual receives the medication; changing it would risk dispensing to the wrong person or violating patient confidentiality. Lastly, the prescriber’s signature signifies their approval and intention; altering it would undermine the concept of a legally binding prescription.

As such, all of these elements are immutable by a pharmacist, emphasizing the importance of maintaining the integrity and authenticity of prescriptions. Therefore, none of these details can be changed, making the selection of "all of the above" the correct response.