Which of the following measures is essential for forklift operation?

Regular maintenance is crucial for forklift operation as it ensures the equipment remains safe, reliable, and efficient. Forklifts undergo significant stress during their use, and regular maintenance helps to identify and rectify potential issues such as mechanical wear, fluid leaks, and brake effectiveness. By conducting regular inspections and servicing, operators can prevent malfunctions that could lead to accidents or operational downtime.

In contrast, while manual lifting techniques, having two operators, and using a rearview mirror have their importance in various contexts, these measures do not directly address the mechanical integrity and operational safety of the forklift itself. Manual lifting techniques pertain more to individual safety when handling materials without equipment. Two operators are not always feasible or necessary, and using a rearview mirror helps with visibility but does not replace the need for a well-maintained machine. These aspects are important for overall safety and efficiency but are secondary to the foundational need for reliable equipment through regular maintenance.