Which of the following represents a formal legal investigation step?

Interviewing relevant persons is a crucial step in a formal legal investigation because it helps to gather firsthand accounts, evidence, and information pertaining to the case in question. This step allows investigators to understand perspectives and insights from individuals who may have witnessed events or have relevant knowledge related to the situation being examined. Such interviews are essential for establishing a timeline, corroborating facts, and identifying any additional areas for further inquiry.

In contrast, providing therapy sessions is more focused on mental health support and does not contribute directly to legal investigations. Offering educational workshops aims at teaching or informing a group and is not an investigative process. Creating public health guidelines serves a preventive or informative purpose and does not involve the specific gathering or analysis of information for a legal case. Therefore, the act of interviewing is distinctly tied to the investigative process, making it the appropriate choice for representing a formal legal investigation step.