Final answer:
The optimum workload for most individuals involves a moderate amount of stress, which enhances performance up to an optimal point beyond which it becomes detrimental.
Step-by-step explanation:
For most people, the optimum workload entails a moderate amount of stress. A moderate level of stress, also referred to as eustress, is associated with positive feelings, optimal health and performance. According to studies like those of Yerkes & Dodson (1908) and Hupbach & Fieman (2012), a moderate amount of stress can enhance memory and efficiency. Performance increases with stress levels up to an optimal point, but beyond this point, stress becomes excessive and debilitating (distress), leading to a decline in performance and adverse health consequences. Therefore, the correct answer is b) Moderate.