Which of the following is NOT included in the definition of a child according to 38 CFR 3.57?

The definition of a child according to 38 CFR 3.57 includes several categories of children recognized for benefits related to veterans' affairs. Specifically, the regulation covers biological offspring, legally adopted children, and stepchildren under specific conditions.

The correct answer, which states that a stepchild not living in the household is not included, aligns with the requirements of the regulation. To qualify as a dependent child for VA benefits, a stepchild generally needs to be part of the veteran's household or meet certain educational criteria. Stepchildren who do not reside with the veteran may not meet the eligibility requirements for benefits and thus are excluded from this definition.

On the other hand, biological offspring and legally adopted children are inherently included in the definition, as they represent direct familial relationships. A stepchild who is attending school between the ages of 18 and 23 is also included in the definition, provided they are dependent on the veteran for support. This reinforces the importance of living arrangements and dependency status in determining eligibility for various benefits provided by the VA.