Final answer:
The tasks, conditions, and standards of PRT activities are primarily derived from the commander's intent, ensuring the training aligns with the mission's objectives and the unit's needs.
Step-by-step explanation:
The tasks, conditions, and standards of Physical Readiness Training (PRT) activities are derived from b. Commander's intent. The commander's intent serves as the foundation for PRT by providing direction that includes the desired end state of training. It is through the commander's guidance that plans are developed to improve and maintain the physical readiness of soldiers, which includes their physical fitness and ability to meet the physical demands of their duties.
Therefore, the correct answer is b. Commander's intent. This direction ensures that PRT programs are focused and aligned with the needs of the unit and the mission objectives. While other factors such as scientific research, soldier feedback, and historical data may influence PRT, the primary source for the tasks, conditions, and standards of these activities is the commander's intent.