Which of the following statements with regard to Black Boxes used in modern aircrafts is/are correct?

1. They carry a beacon emitting red light pulses to facilitate underwater detection.

2. They record both the cockpit voice and flight data.

3. Their memory units are made using either stainless steel or titanium.

Detailed Explanation of the Statements: Statement 1 is INCORRECT: Black boxes do use a beacon to help search teams find them underwater, but it is an acoustic beacon (sound), not a visual one (light). This device is called an Underwater Locator Beacon (ULB). When the black box gets submerged in water, the acoustic sensor automatically triggers a "pinging" sound at a specific frequency ($37.5\text{ kHz}$) that can travel through water for up to 30 days. Red light pulses would be completely useless in the deep, dark, and murky depths of an ocean. Statement 2 is CORRECT: A modern aircraft actually carries a combination of two black box systems: the Cockpit Voice Recorder (CVR), which records crew conversations and cockpit radio communications, and the Flight Data Recorder (FDR), which tracks physical parameters like altitude, airspeed, wing flap positions, and engine performance.  Statement 3 is CORRECT: To ensure that the critical flight data survives catastrophic crashes, massive explosions, intense fires, and extreme deep-sea pressure, the Crash-Survivable Memory Unit (CSMU) is heavily armored. The outer protective housing of the memory boards is typically forged from thick stainless steel or titanium, insulated with high-temperature thermal blocks.Quick Facts: The Aviation "Black Box"The Color Irony: Despite the name, black boxes are never painted black. They are painted bright fluorescent orange to make them easily visible among the debris of a crash site.Survival Capabilities: They are engineered to survive impacts of up to $3,400\text{ Gs}$ (gravitational force) and temperatures exceeding $1,100^\circ\text{C}$ for over an hour.