The correct option is "2 and 3 only" because black boxes, or flight data recorders, function by capturing both cockpit voice and flight data, which are critical for post-incident investigations. Moreover, these devices are designed to withstand extreme conditions and are typically housed in protective casings made from robust materials such as stainless steel or titanium. While black boxes are equipped with emergency locator transmitters (ELTs) that emit signals for recovery, they do not specifically emit red light pulses for underwater detection, thus making statements 1 incorrect. Understanding the composition and functionality of black boxes is essential for comprehending aviation safety mechanisms and accident investigation protocols, key components in the broader context of aerospace engineering and aviation regulations relevant for UPSC examination preparation.