The absence of bowel sounds is established after listening for:

A. 2 full minutes: Listening for 2 minutes is insufficient to determine the absence of bowel sounds reliably.B. 1 full minute: One minute is also too brief, as bowel sounds can sometimes be infrequent, especially in certain conditions.C. 5 full minutes. The absence of bowel sounds is confirmed after listening in each quadrant for a minimum of 5 full minutes. This is necessary to ensure that the lack of sounds is not due to temporary decreased activity and is instead a true absence, which may indicate a medical emergency like a bowel obstruction.D. 1 1/2 minutes: This time is not long enough to confirm the absence of bowel sounds accurately.