Which of the following is NOT a method used by investigators to gather information?

The reasoning behind identifying conducting public opinion polls as not a method used by investigators to gather information is that it is primarily a tool for gauging public sentiment or attitudes rather than collecting specific, actionable intelligence related to a criminal investigation. Investigators typically focus on methods that directly aid in solving crimes or gathering evidence, such as profiling suspects to establish behavioral patterns, using surveillance to monitor activities and movements, and employing digital forensics to recover and analyze data from electronic devices. Each of these methods provides concrete information relevant to ongoing investigations, whereas public opinion polls are more exploratory and general in nature, lacking the specificity required for criminal cases.