To begin talking with a newly admitted patient about pain management, the nurse would most appropriately state:

A. Evaluation:
Evaluation involves the assessment of a patient's response to nursing interventions and the effectiveness of the care plan. In this scenario, the nurse is not evaluating the patient's response to previous interventions but is rather in the process of conducting a new assessment.

B. Assessment:
This statement is correct. The nurse is in the assessment phase of the nursing process. She is collecting data by checking the patient's record, performing a physical examination (digital rectal exam), and noting the patient's complaint and signs of constipation (no bowel movement for three days, hard stool). Assessment is the first step of the nursing process and involves data collection to identify health problems and needs.

C. Nursing Diagnosis:
Nursing diagnosis involves analyzing the data collected during the assessment to identify actual or potential health problems. The nurse has not reached the stage of formulating a nursing diagnosis in this scenario; she is still gathering data.

D. Implementation:
Implementation is the phase of the nursing process where nursing interventions are carried out based on the nursing care plan. The nurse is not implementing interventions yet but is still in the process of data collection.

A. "Don't worry; this pain won't last forever."
This statement dismisses the patient's concerns and does not encourage open communication about pain. It does not address the patient's current pain experience or provide a basis for effective pain management.

B. "You look pretty comfortable. Are you having any pain?"
While this statement attempts to inquire about the patient's pain, it might not encourage the patient to open up about their pain experience. The patient might downplay their pain to appear strong or not to be a bother.

C. "Is this pain the same as the pain you had yesterday?"
This question is specific and might help in assessing the consistency and nature of the pain. However, it assumes the patient had pain yesterday and does not open the conversation effectively for the patient to express their pain experience freely.

D. "Tell me about the pain you've been having."
This statement is open-ended and encourages the patient to express their pain experience in their own words. It creates a comfortable environment for the patient to discuss their pain, allowing the nurse to gather valuable information about the pain's intensity, location, quality, and factors that aggravate or alleviate it. This approach is patient-centered and allows for a comprehensive pain assessment.