How is a "child" defined under INA § 101(b)(1)?

The definition of "child" under INA § 101(b)(1) is specifically aimed at ensuring clarity in various immigration contexts. According to this statute, a "child" is defined as an individual who is under 21 years of age and unmarried. This distinction is crucial for several immigration benefits, including petitions filed by parents for their children to obtain visas or lawful permanent residency.

The emphasis on being unmarried is significant because it differentiates this definition from different categories of individuals. For instance, if an applicant is married, they would not qualify as a child under this provision, regardless of their age. The age limit ensures that the term "child" encompasses those who are typically considered dependents, which is vital for family-based immigration processes.

In summary, option B accurately captures the intended definition as per INA § 101(b)(1), focusing on the criteria of being under 21 years of age and unmarried, which is essential for understanding eligibility in immigration applications and petitions.