Final answer:
When starting a forklift, an operator should pay close attention to nearby pedestrians to maintain safety. Other options listed are not as immediately relevant when operating such machinery.
Step-by-step explanation:
When starting the forklift, an operator should pay the most attention to A) Nearby pedestrians. This is crucial for ensuring the safety of everyone in the work area and preventing accidents. A human factors psychologist would be concerned about aspects of an office workstation that affect the well-being and productivity of the worker, such as the height of the chair (a). All other listed options like the operator's lunch break time, weather forecast for the day, and office emails, though potentially relevant to the operator's day, are not the immediate concerns when starting a forklift.