## Core Concept
The question pertains to the assessment of intellectual disability, formerly known as mental retardation, which is characterized by significant limitations in both intellectual functioning and adaptive behavior. The Intelligence Quotient (I.Q.) is a score derived from standardized tests designed to measure human intelligence. The mental age, chronological age, and I.Q. are related by the formula: I.Q. = (Mental Age / Chronological Age) * 100.

## Why the Correct Answer is Right
Given that the 16-year-old male has a mental age of 9 years, we can calculate his I.Q. as follows: I.Q. = (9 / 16) * 100 = 56.25. Intellectual disability is generally defined by an I.Q. score below 70. The classification of intellectual disability based on I.Q. scores is as follows: mild intellectual disability (I.Q. 50-69), moderate (I.Q. 35-49), severe (I.Q. 20-34), and profound (I.Q. below 20). Therefore, an I.Q. score corresponding to a mental age of 9 in a 16-year-old falls in the mild intellectual disability range.

## Why Each Wrong Option is Incorrect
- **Option A:** Without a specific I.Q. score or mental age provided, it's impossible to directly assess its accuracy, but given the correct answer, it can be inferred that option A does not correspond to an I.Q. score or classification consistent with a mental age of 9 in a 16-year-old.
- **Option B:** Similarly, without specifics, we can't directly calculate, but if it doesn't match the mild intellectual disability category based on the provided mental and chronological ages, it's incorrect.
- **Option C:** This option is not provided, but presumably, if it does not align with the calculated I.Q. and corresponding intellectual disability classification, it's incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that intellectual disability is categorized into four levels based on I.Q. scores: mild, moderate, severe, and profound. Additionally, adaptive behaviors, which include practical, social, and conceptual skills, are crucial in the diagnosis and assessment of intellectual disability. The assessment of intellectual disability should consider both I.Q. scores and adaptive functioning.

## Correct Answer: D.