**Core Concept:** The first disability census is a survey aimed at determining the prevalence and impact of disabilities in a population. This is important for planning healthcare services, policies, and resources to improve the lives of individuals with disabilities.

**Why the Correct Answer is Right:** The correct answer, B 1871, refers to the British census conducted by Sir Edwin Chadwick, which recorded the number of individuals with disabilities and their associated disabilities. This census marked the beginning of systematic data collection on disabilities and their prevalence.

**Why Each Wrong Option is Incorrect:**

A. 1948 (UN Convention on the Rights of Persons with Disabilities): While this is a significant event in the history of disability rights, it is not the year when the first disability census was conducted.

C. 1950 (World Health Organization): Although the World Health Organization was established in 1948, the first disability census was conducted in 1871, not in the year of WHO's creation.

D. 1960 (United Nations): Similar to options A and C, the first disability census happened in 1871, not in the year the UN was founded.

**Clinical Pearl / High-Yield Fact:** Disability census data is crucial for understanding the health needs and requirements of individuals with disabilities, thus informing healthcare policies and resource allocation.

**Correct Answer:** B 1871

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The **first disability census** was conducted in the United Kingdom in 1871 by Sir Edwin Chadwick. This census aimed to determine the prevalence and impact of disabilities on the population, which helped to establish healthcare services and policies tailored to the needs of individuals with disabilities. The data collected from this census laid the foundation for understanding the health-related requirements of people with disabilities, ultimately influencing healthcare policies and resource allocation.