Final answer:
The WPPSI-IV test structures are designed for children aged 2 years, 6 months to 7 years, 7 months, which corresponds to option (a) in the student's question.
Step-by-step explanation:
The age ranges for the different test structures in the Wechsler Preschool and Primary Scale of Intelligence-Fourth Edition (WPPSI-IV) span from 2 years 6 months to 7 years 7 months. This means the correct answer to the question is option a) 2 years, 6 months to 7 years, 7 months. The WPPSI-IV is carefully designed to assess the cognitive development levels of children within this specific age group. It is crucial to note that for children ages 0 to 2.5, 6-13, and 13-20, different assessment tools and methods, which are age-appropriate, would need to be used.