Final answer:
Conducting surveys by mail/email is a data collection method used in research, particularly within the social sciences for gathering large amounts of data that can be generalized to a broader population.
Step-by-step explanation:
Of the options given, Option 2: Conducting surveys by mail/email is a data collection method used in research. Surveys are a fundamental tool in research methods, facilitating the collection of data from subjects who respond to questions about behaviors and opinions, typically in the form of a questionnaire. These can be distributed and conducted in various ways, including online, over the phone, by mail, or face-to-face, each providing varying levels of anonymity and engagement from the participants. Surveys are valuable for collecting data from large numbers of individuals and are especially useful in the social sciences when researchers aim to generalize findings to a broader population. While there may be drawbacks, such as the potential bias in self-reported data, surveys overall offer a structured approach to gathering information critical for empirical studies.