The diathesis-stress model proposes that a disorder may develop when:

• A. An underlying vulnerability is coupled with a precipitating event.
• B. A single genetic mutation causes all cases.
• C. Only environmental stressors cause the disorder.
• D. Only symptoms during adolescence cause the disorder.

Answer: (A)

The idea being tested is that a disorder develops when an underlying vulnerability interacts with a triggering event. The vulnerability, or diathesis, can come from genetics, biology, or early life experiences that leave someone predisposed but not yet ill. A stressor or precipitating event—such as a major life change, trauma, or sustained pressure—can push that person over the threshold into symptoms. This explains why not everyone with risk factors becomes ill, and why the same stressor can have different effects across individuals depending on their level of vulnerability. The other options don’t fit because they either imply a single cause, ignore the need for an underlying predisposition, or focus on a factor (like adolescence) without acknowledging how vulnerability and stress interact.