Final answer:
To assess fetal heart tones in a client who is at the end of her first trimester, the nurse should begin with the lower left quadrant, since this is typically where the fetal back and heart tones are easily detectable at this stage.
Step-by-step explanation:
The nurse caring for a pregnant client who is at the end of her first trimester will typically begin assessing the fetal heart tones by placing the Doppler ultrasound stethoscope in the lower abdominal quadrants, as this is where the uterus is located at this stage of pregnancy. Specifically, the nurse should start with the lower left quadrant, which is option a). This area is often used as a starting point because the fetal back, where the heart tones are most easily detected, is frequently positioned on the left side of the uterus during the first trimester. However, if the heartbeat is not readily found here, the nurse may also check the lower right quadrant, as fetal position can vary.