**Core Concept**
Disability-adjusted life expectancy (DALE) is a measure used to quantify the average number of years a person can expect to live in full health, accounting for both mortality and disability. DALE takes into consideration the years lived in full health, years lived with disability, and years of life lost due to premature mortality. This concept is crucial in understanding the impact of various health conditions on an individual's quality of life.

**Why the Correct Answer is Right**
The correct answer to this question is Disability-Adjusted Life Years (DALYs). DALYs is a more comprehensive measure that combines years of life lost (YLL) due to premature mortality and years lived with disability (YLD). This allows for a more accurate representation of the overall burden of a disease on a population. The World Health Organization (WHO) uses DALYs as a key metric in assessing the global health impact of various conditions. This measure is particularly useful in evaluating the effectiveness of interventions aimed at reducing the burden of disease.

**Why Each Wrong Option is Incorrect**
**Option A:** Life expectancy at birth (LEB) is a measure of the average number of years a person born in a given year can expect to live, but it does not account for disability. Therefore, it is not a replacement for DALE.

**Option B:** Disability-free life expectancy (DFLE) is a measure of the average number of years a person can expect to live free from disability, but it does not account for mortality. Hence, it is not a replacement for DALE.

**Option C:** Quality-adjusted life years (QALY) is a measure that takes into account both the quality and quantity of life, but it is not a direct replacement for DALE. QALYs are often used in economic evaluations of healthcare interventions.

**Clinical Pearl / High-Yield Fact**
DALYs is a key metric in global health, and it has been widely adopted as a tool for evaluating the burden of disease and the effectiveness of interventions. This measure is particularly useful in assessing the impact of diseases such as HIV/AIDS, tuberculosis, and malaria, which have a significant burden on low- and middle-income countries.

**Correct Answer: C. Disability-Adjusted Life Years (DALYs)**