Final answer:
When using a biphasic defibrillator and the recommended dosage is not known, it is best to shock using the minimum energy dose available option (B).
Step-by-step explanation:
In the case where the recommended dosage is not known when using a biphasic defibrillator, the correct approach would be to shock using the minimum energy dose available option (B). This is because it is important to deliver the shock as soon as possible in order to restore the normal heart rhythm.
While the other options may be available, it is best to start with the minimum energy dose to minimize any potential harm to the patient.
It is important to note that in a real-life scenario, it is crucial to consult with medical professionals and follow the appropriate guidelines and protocols.