A nurse is teaching a client about family planning using the basal body temperature method. Which of the following instructions should the nurse include in the teaching?

A. Take your temperature every night before going to bed: Nighttime readings are not basal body temperatures. B. Take your temperature 1 hour after getting out of bed: This does not reflect the true basal temperature. C. Take your temperature immediately after waking and before getting out of bed: This ensures an accurate basal temperature, as any activity can alter the reading. D. Take your temperature within 30 minutes after your first morning void: BBT should be measured before any activity, including voiding.