Final answer:
The appropriate reasons to use observational methods are to study natural behavior in real-world settings and to minimize researcher impact on participant behavior; they are not typically used to investigate cause-and-effect relationships or to control extraneous variables.
Step-by-step explanation:
The appropriate reasons to use an observational method to collect data are varied and depend on the research question and context. However, some of the key reasons include B) to study natural behavior in a real-world setting which provides valid, true-to-life information, and C) to minimize the impact of the researcher on participant behavior to capture accurate data of how individuals or groups behave naturally without experimental manipulation. It's crucial to note that observational methods are not typically used A) to investigate cause-and-effect relationships, as they cannot control for extraneous variables that might influence the outcome. Also, observational methods are generally not used D) to control extraneous variables, since they do not manipulate conditions but rather observe them as they naturally occur.