Step 1: Understanding the Concept:
Stressors can be categorized by their source. An environmental stressor is a source of stress that comes from the physical environment.
Step 2: Detailed Explanation:
(A) Frustration and (C) Tension: These are internal psychological states; they are responses to stressors, not the environmental stressors themselves.
(D) Divorce: This is a major life event and is typically classified as a social or personal stressor, as it relates to interpersonal relationships and social roles.
(B) Earthquake: This is a large-scale event occurring in the physical environment. Natural disasters, pollution, noise, extreme temperatures, and crowding are all examples of environmental stressors.
Step 3: Final Answer:
An earthquake is a classic example of an environmental stressor.