Identify a significant risk factor for developing post-traumatic stress disorder (PTSD).

Experiencing severe trauma is indeed a significant risk factor for developing post-traumatic stress disorder (PTSD). PTSD can occur after an individual has been exposed to a traumatic event that poses a serious threat to their physical safety or life. This could include situations such as military combat, sexual assault, natural disasters, or serious accidents. The intensity and severity of the trauma play a crucial role in the likelihood of PTSD developing. When an individual goes through a severe trauma, their psychological response can lead to persistent and debilitating symptoms that meet the criteria for PTSD, such as intrusive thoughts, emotional numbness, and hyperarousal.

In contrast, experiences of mild stress, having a supportive family, and participating in regular therapy are generally not considered direct risk factors for PTSD. Mild stress typically does not have the same potential to overwhelm an individual's capacity to cope as severe trauma does. A supportive family may actually serve as a protective factor by providing emotional and practical support, which can mitigate the effects of trauma. Similarly, engaging in regular therapy can be beneficial in processing traumatic experiences and developing coping strategies, reducing the risk of PTSD rather than increasing it.