Final answer:
The example of demographic information among the given options is 'a. Occupation'. Demographic data often includes statistics like age, sex, marital status, and occupation, which are collected by governments through censuses and registries.
Step-by-step explanation:
The question asks to identify which option is an example of demographic information. Demographic data refers to statistics about humans in a population. These are often collected through sources like vital statistics registries and national censuses. This kind of data includes information on variables such as age, sex, marital status, education, employment status, and occupation. Therefore, the correct answer to the question is "a. Occupation." Interests, biases, and beliefs, while they may be influenced by demographics, are not in themselves demographic data.