Final answer:
The collection of objective and subjective data falls under the 'Assessment' phase of the nursing process. It is crucial for understanding a patient's condition and determines the subsequent steps in their care.
Step-by-step explanation:
The part of the nursing process that involves the collection of objective and subjective data is a) Assessment. The assessment phase is critical in nursing as it involves gathering crucial information about the patient's physical condition, medical history, and current symptoms. Subjective data include the patient's own description of their health and symptoms, while objective data are measurable facts such as vital signs, lab results, and physical examination findings. This is the first step before moving on to diagnosis, planning, and implementation.