Okay, let's tackle this question about the Human Development Index (HDI). First, I need to recall what HDI is. From what I remember, HDI is a composite index that measures average achievement in three basic dimensions of human development: a long and healthy life, knowledge, and a decent standard of living. The dimensions are typically measured by life expectancy at birth, mean years of schooling and expected years of schooling, and GDP per capita adjusted for purchasing power parity (PPP).

The question is asking which statement is true about HDI. Since the options A to D aren't provided, I have to think of common misconceptions or true statements that might be tested. Let's consider possible options that are often confused.

One common misconception is that HDI is calculated using GNI per capita alone. But actually, HDI combines GNI per capita with life expectancy and education. Another point is that HDI is a composite index, which might be a key point. Also, HDI is developed by the United Nations Development Programme (UNDP), so if any option mentions UNDP, that's likely correct.

Another possible true statement is that HDI ranks countries based on their level of human development, categorizing them as very high, high, medium, or low. For example, Norway often tops the HDI rankings. Also, HDI doesn't account for inequality within countries, which is why the Inequality-adjusted HDI (IHDI) was introduced. If an option says HDI accounts for inequality, that's incorrect.

Let me structure the answer based on these points. The core concept is that HDI is a composite index measuring three dimensions. The correct answer would highlight that it's a composite index. The incorrect options might incorrectly state that HDI is calculated using only one parameter, or that it's developed by a different organization. The clinical pearl here is to remember the three components and the UNDP as the developer.

**Core Concept**
The Human Development Index (HDI) is a composite statistic developed by the United Nations Development Programme (UNDP) to measure human development across three dimensions: **life expectancy**, **education**, and **standard of living** (GNI per capita). It provides a broader perspective on development than GDP alone.

**Why the Correct Answer is Right**
The correct statement would emphasize HDI's composite nature, combining **life expectancy at birth**, **mean and expected years of schooling**, and **GNI per capita (PPP)**. These metrics are normalized and aggregated into a single index, categorizing countries into "very high," "high," "medium," or "low" human development. The UNDP annually publishes HDI rankings, with Norway consistently ranking highest.

**Why Each Wrong Option is Incorrect**
**Option A:** *If it claims HDI uses only GDP per capita*—HDI integrates **three dimensions**, not just economic indicators.
**Option B:** *If it states HDI is calculated by the World Bank*—HDI is specifically developed by the **UNDP**, not the World Bank.
**Option C:** *If it says HDI accounts for inequality*—HDI does **not** adjust for inequality; the **Inequality-adjusted HDI (IHDI)** addresses this limitation.
**Option D:** *If it asserts HDI includes crime rates*—HDI excludes non-material aspects like safety or environmental sustainability.

✓ Correct Answer: C. Life expectancy- Birth