What constitutes proof of age for an unaccompanied minor?

The correct choice is that proof of age for an unaccompanied minor can be established through a birth certificate or passport. These documents provide official confirmation of the child's date of birth and identity, which is crucial for verifying their status as an unaccompanied minor when traveling.

Birth certificates are specifically designed to document an individual's birth details, making them a reliable source for confirming age. Passports also serve this purpose, as they contain the holder's date of birth and are widely accepted as valid identification internationally, ensuring that the child's travel complies with airline policies and regulations regarding unaccompanied minors.

Other choices, while they may serve as forms of identification in different contexts, do not provide the same level of official age verification as a birth certificate or passport. A government-issued ID card could potentially be accurate, but it’s not specifically designed for minors, and many children do not possess one. School identification may provide some information but lacks the legal authority of a birth certificate or passport. A parental consent letter is important for permission but does not serve as proof of age.