Which of the following statements are true of research conducted on the relationship of overload, underload, and stress among employees? Multiple select question. The best balance of challenge, reward, and responsibility can only be achieved through high stress. Employees on the low and high ends of the stress ranges reported serious medical problems. Stress in any form and to any degree is undesirable and adversely affects productivity. The relationships among stress, stressors, and disease are likely to be curvilinear