Stress" is defined as a. a negative emotion resulting from environmental unpleasantness b. the interpretation of specific events as threatening or challenging c. environmental factors that result in anxiety d. the physiological reaction of the body to environmental factors

I think the answer is B, the interpretation of specific events as threatening or challenging. According to Hans Selye stress is a body's nonspecific response to any demand made on it, physical arousal to events seen as threatening, and mental arousal to events seen as challenging. However, there are effective strategies to cope with stress which include a sense of humor, relaxation, social skills, and social support.