What is true about a taxpayer's unmarried child who did not provide more than half of their own support and lived with the taxpayer all year?

A taxpayer's unmarried child who did not provide more than half of their own support and lived with the taxpayer for the entire year indeed meets the criteria to be considered a qualifying child. This designation is significant because it allows the taxpayer to claim various tax benefits, such as the Child Tax Credit and the Earned Income Tax Credit.

Additionally, because the child meets the criteria for dependency—being unmarried and living with the taxpayer, as well as not providing more than half of their own support—they can also be classified as a qualifying person for certain tax benefits. Qualifying persons are defined under tax law to help determine eligibility for specific deductions and credits.

This recognition of both aspects means that the taxpayer can take advantage of the benefits tied to having a qualifying child while also acknowledging the child's status as a qualifying person for additional tax considerations. Therefore, the correct answer underscores both the status of the child as a qualifying child and the related tax advantages that come with that classification.