## Core Concept
The Intelligence Quotient (IQ) is a measure used to assess human intelligence, which encompasses various cognitive abilities such as reasoning, problem-solving, and thinking. It is often calculated through standardized tests that compare the test-taker's performance to that of a large sample of people who have taken the test before. The concept of IQ is rooted in **psychometrics**, the science of measuring mental capacities and processes.

## Why the Correct Answer is Right
The correct formula for calculating IQ is: **IQ = (Mental Age / Chronological Age) * 100**. This formula was one of the first methods used to calculate IQ and is still referenced today. Mental age is determined by the performance on intelligence tests relative to the average performance of people of the same chronological age. For example, if a 10-year-old child performs on an intelligence test at a level expected of a 12-year-old, their mental age would be 12, and their IQ would be (12/10)*100 = 120.

## Why Each Wrong Option is Incorrect
- **Option A:** [Not provided] - Since the actual option A is not provided, we cannot assess its accuracy.
- **Option B:** [Not provided] - Similarly, without the content of option B, we cannot evaluate its correctness.
- **Option C:** [Not provided] - The same applies to option C; without details, we cannot determine why it is incorrect.
- **Option D:** [Not provided] - Option D's inaccuracy cannot be evaluated without its content.

## Clinical Pearl / High-Yield Fact
A key point to remember is that IQ scores are **standardized** to have a mean of 100 and a standard deviation of 15 in the general population. This allows for easy interpretation of scores: about 68% of the population will score between 85 and 115, and about 95% will score between 70 and 130. Understanding this distribution is crucial for interpreting IQ scores in clinical and educational settings.

## Correct Answer: D. Mental age/ chronological age*100