Main types of assessment measures used by psychologists to study the outcomes of mental activity are:

1. Behavioral measures:
- Behavioral measures involve the observation and recording of an individual's overt behavior in various situations. This can include tasks, activities, or responses that provide insight into the individual's cognitive processes, emotions, or personality traits. Examples of behavioral measures include performance on cognitive tasks, response time, and task completion accuracy.

2. Self-report measures:
- Self-report measures involve individuals providing information about their thoughts, feelings, and behaviors through questionnaires, surveys, or interviews. These measures rely on individuals' subjective perceptions and interpretations of their own experiences. Examples of self-report measures include personality inventories, depression scales, and anxiety questionnaires.

3. Physiological measures:
- Physiological measures involve the assessment of physiological responses or changes in the body that can provide insight into an individual's mental activity. These measures typically involve monitoring bodily functions such as heart rate, blood pressure, brain activity (using techniques like electroencephalography), or skin conductance. Physiological measures can provide objective data about an individual's physiological arousal, emotional states, or cognitive processing.

Why option D is correct?

The correct answer is option D, which includes behavioral, self-report, and physiological measures. This is because psychologists use a combination of these assessment measures to study the outcomes of mental activity comprehensively. Each type of measure has its own strengths and limitations, and using a combination of measures allows researchers to gather a more comprehensive understanding of an individual's mental processes.

- Behavioral measures provide insight into an individual's overt behavior and can be used to assess cognitive processes, emotions, or personality traits. They are useful for studying observable aspects of mental activity and can provide valuable information about an individual's performance on tasks or activities.

- Self-report measures rely on individuals' subjective perceptions and interpretations of their own experiences. They can provide insights into an individual's thoughts, feelings, and behaviors that may not be directly observable. Self-report measures are particularly useful for studying aspects of mental activity that are not easily measurable through behavioral or physiological means, such as attitudes, beliefs, or subjective well-being.

- Physiological measures allow researchers to directly measure and quantify physiological responses or changes in the body that are associated with mental activity. These measures provide objective data and can be used to study aspects of mental activity such as physiological arousal, emotional states, or cognitive processing. Physiological measures complement behavioral and self-report measures by providing a more objective and physiological perspective on mental activity.

In conclusion, psychologists use a combination of behavioral, self-report, and physiological measures to study the outcomes of mental activity comprehensively. Each type of measure provides a different perspective and contributes to a more comprehensive understanding of an individual's mental processes.