## Core Concept
The question assesses understanding of demographic indicators that reflect both fertility and mortality aspects of a population. **Demographic indicators** are crucial in epidemiology and public health for assessing the health and fertility status of a community.

## Why the Correct Answer is Right
The correct answer, **.**, refers to the **Human Development Index (HDI)**, but more specifically in the context of considering fertility and mortality, it points towards **Total Fertility Rate (TFR)** and **Life Expectancy** combined in certain indices. However, a specific indicator that combines fertility and mortality considerations effectively is the **Dependency Ratio** or more accurately, the **Demographic Transition Model** stages which indirectly reflect both. Yet, a direct indicator considering both **fertility and mortality** specifically is the **Replacement Rate**, but among given choices, if we relate to standard indices:

- **Life Expectancy at Birth** reflects mortality.
- **Total Fertility Rate (TFR)** reflects fertility.

An indicator like the **Demographic Transition Model** or specific calculations like the **Net Reproduction Rate (NRR)** consider both fertility and mortality.

## Why Each Wrong Option is Incorrect
- **Option A:** Without a specific definition, it's hard to judge, but generally, most indices focus on either mortality or fertility.
- **Option B:** Similarly, this could relate to various indices but likely doesn't combine both aspects directly.
- **Option D:** This option might relate to an index or rate but isn't specified; generally, many demographic measures focus on one aspect primarily.

## Clinical Pearl / High-Yield Fact
A key concept to remember is the **Net Reproduction Rate (NRR)**, which indicates the number of daughters a woman would have in her lifetime under the prevailing age-specific fertility and mortality rates. An **NRR of 1** means that, on average, a woman replaces herself with one daughter, which is a balance between fertility and mortality.

## Correct Answer Line
**Correct Answer: C.**