Final answer:
A nurse must obtain parental consent before providing medical care to a minor. If parents are unavailable, legal guardianship must be confirmed for any other caretakers to consent.
Step-by-step explanation:
Before providing medical care to Charlie, who is suspected of having an allergic reaction, the nurse must first obtain parental consent. This is necessary because children cannot legally provide consent for themselves, and it is the responsibility of the parents or legal guardians to give consent for medical treatments on behalf of the minors. If the parents are not available, as in Charlie's case because they are serving in the military overseas, the nurse needs to verify that the aunt and uncle have been granted the authority to give consent, potentially through legal guardianship or a documented power of attorney.