Final answer:
The planning phase is the part of the nursing process that mainly involves establishing priorities, which are essential for creating effective patient care plans.
Step-by-step explanation:
The phase of the nursing process that most involves establishing priorities is the planning phase. This is the stage where nurses develop a plan of action based on the assessment data collected about the patient's health status. Priorities are set to address the most immediate and significant health issues first, guiding interventions while ensuring patient safety and outcome effectiveness. This process is crucial for delivering personalized patient care. Nurses must carefully assess, analyze, and prioritize nursing diagnoses and interventions to provide safe and effective care to their patients.