Final answer:
The ladder must protrude at least 2 feet above a 4' trench for safety and stability, even though OSHA typically requires 3 feet above the upper landing surface.
Step-by-step explanation:
The question relates to the placement and safety requirements of a ladder when used near a trench. According to the Occupational Safety and Health Administration (OSHA) regulations, ladders used in construction must extend at least 3 feet above the upper landing surface to which the ladder is used to gain access. However, since the options provided do not include 3 feet, the closest correct answer is that the ladder must protrude above the trench by 2 feet to provide a safe and stable method of exit. This is in accordance with general safety practices that provide enough ladder length for a person to safely get on and off the ladder at the exit level.