Explanation:

The correct answer is option B - "The chemist didn't believe the prescription was legitimate." This means that the chemist refused to give the narrator the prescribed medicines because he/she doubted the authenticity or validity of the prescription.

Reasoning:

There could be several reasons why the chemist didn't believe the prescription was legitimate. Some possible reasons include:

1. Suspicious prescription: The chemist may have found something suspicious or unusual about the prescription, such as illegible handwriting, missing information, or an unfamiliar doctor's name. This could have raised doubts in the chemist's mind regarding the authenticity of the prescription.

2. Frequent prescriptions: If the narrator frequently visits the chemist for the same or similar medications, the chemist might suspect that the prescriptions are not genuine. This could be a sign of drug misuse or abuse, leading the chemist to refuse to provide the medications.

3. Unusual dosage or medication: If the prescribed medication or dosage is uncommon or not typically prescribed for the given condition, the chemist may question the legitimacy of the prescription. In such cases, the chemist may consult with a healthcare professional or contact the prescribing doctor to verify the prescription before dispensing the medication.

4. Lack of supporting information: The chemist may require additional information or documentation to verify the prescription, such as a valid ID or insurance details. If the narrator fails to provide the necessary information, the chemist may refuse to dispense the medications.

5. Past experiences: If the chemist has had previous encounters with forged or fraudulent prescriptions, he/she may become more cautious and skeptical when presented with new prescriptions. This could lead to the chemist questioning the legitimacy of the prescription and declining to provide the medications.

In any case, it is the chemist's responsibility to ensure the safety and legality of dispensing medications. If there are any doubts regarding the authenticity of a prescription, it is important for the chemist to follow the appropriate protocols and seek clarification or verification from the prescribing doctor or relevant authorities.