Final answer:
B) Chronic irritability and agitation is the personality characteristic often associated with both Depression and Psychasthenia, aligning with attributes of neuroticism.
Step-by-step explanation:
The personality characteristic often associated with both Depression and Psychasthenia is chronic irritability and agitation (B). Neuroticism, which has been linked to a tendency to experience negative emotions like anxiety, moodiness, and sadness, often manifests as chronic health problems and emotional disturbances which can include depression and psychasthenia. People high on neuroticism tend to experience emotional instability and are characterized as angry, impulsive, and hostile, which aligns with the options referring to chronic irritability and agitation. Studies have shown that individuals with a higher tendency toward neuroticism are also at greater risk for developing major health issues and facing mortality.