The correct answer is D. Census data is collected through a combination of door-to-door surveys, online questionnaires, and sampling methods.
Door-to-door surveys are the most common method of collecting census data. Census workers visit households and ask residents questions about their demographics, housing, and employment. Online questionnaires are becoming increasingly popular as a way to collect census data. These questionnaires can be completed by residents at their own convenience and can be accessed by people who may not be able to participate in a door-to-door survey. Sampling methods are used to collect data from a subset of the population. This is done to save time and money, as it is not possible to collect data from every person in the country.
Each of these methods has its own advantages and disadvantages. Door-to-door surveys are the most accurate way to collect data, but they can be expensive and time-consuming. Online questionnaires are less expensive and time-consuming, but they may not be as accurate as door-to-door surveys. Sampling methods are the least expensive and time-consuming method, but they may not be as accurate as door-to-door surveys or online questionnaires.
The Census Bureau uses a combination of these methods to collect data that is as accurate and up-to-date as possible.