Final answer:
People with a quick temper or who are easily upset are high in neuroticism, which is associated with emotional instability and a predisposition to negative emotions.
Step-by-step explanation:
People who are easily upset or have a quick temper are high in neuroticism. Neuroticism is a personality trait that corresponds to the tendency to experience negative emotions such as anxiety, anger, and depression. Those with high levels of neuroticism may exhibit emotional instability and are often described as having a quick temper, being impulsive, and sometimes acting in a hostile manner.
In contrast to neuroticism, individuals who score low on this trait tend to be described as calm and even-tempered, showing emotional stability. According to the Eysencks' theory, the two main dimensions of personality are extroversion/introversion and emotional stability/instability. The high end of the emotional stability/instability spectrum is characterized by neuroticism, which is associated with a more reactive sympathetic nervous system and a readiness to experience fight-or-flight reactions even in low-stress situations.
Therefore, the answer to the question "People who are easily upset or have a quick temper are high in what?" is c) neuroticism.