Which of the following is a trait of a child affected by a mother's alcohol use during pregnancy?

A child affected by a mother's alcohol use during pregnancy is likely to exhibit a range of developmental issues, one of which includes mental retardation or intellectual disability. This condition is associated with fetal alcohol spectrum disorders (FASDs), which result from prenatal exposure to alcohol. Such exposure can lead to significant cognitive impairments, learning disabilities, and behavioral problems.

The other traits listed do not typically align with the outcomes associated with prenatal alcohol exposure. Strong social skills and high IQ are generally positive attributes that can be influenced by a nurturing and supportive environment, which may be lacking in the context of FASDs. Advanced physical development might not be characteristic either, as children with these disorders often experience growth deficits and other physical anomalies. Thus, the identification of mental retardation as a trait reflects the serious cognitive and developmental impacts that can arise from maternal alcohol use during pregnancy.