CEH v13 stresses the importance of passive reconnaissance when the goal is to avoid any interaction with the target's systems. Job postings frequently reveal detailed information such as internal technologies, OS platforms, security tools, IDS brands, virtualization environments, scripting languages, and cloud services.
CEH explicitly notes job ads as one of the richest passive intelligence sources because organizations inadvertently disclose their tech stack, often mentioning required experience with specific network components, databases, protocols, or internal tools. Options B and D involve direct interaction, violating the passive reconnaissance requirement. WHOIS lookups (Option C) provide DNS registrar information but do not reveal internal network details. Job postings, social media recruitment materials, and HR documentation are discussed in CEH as critical OSINT resources used during the footprinting phase to gather actionable intelligence while maintaining complete stealth. Thus, analyzing job postings is the correct method.