Final answer:
A Registration System in demographics refers to the Registration technique used for recording vital events like births and deaths, crucial for calculating demographic measures.
Step-by-step explanation:
A Registration System in demographics refers to the method of recording vital events such as births, deaths, marriages, and migrations. Among the given options, d) Registration technique is directly associated with this system. The registration technique is a method employed by governments to collect and maintain these important events for demographic analysis. Meanwhile, a census is conducted typically every 10 years to count and collect data on population variables such as age, sex, and employment. De facto and de jure are terms related to types of segregation, with de facto being segregation that exists in reality (often unofficially), while de jure is segregation that is enforced by law. Neither of these terms pertains directly to the registration of vital events.
Demographic data collected through the registration technique is crucial in understanding population dynamics and developing policies. This data is vital in calculating demographic measures such as the birth rate, death rate, fertility rate, and replacement fertility rate. These indicators can help demographers assess the health and growth of a population, as well as other elements like the effects of youth bulge phenomenon on social and economic factors.