In "One War Ends, Another Begins," the author emphasizes the challenges Clara faced primarily through the worried expression on the doctor’s face. This image conveys the seriousness of Clara's situation and the gravity of the challenges ahead of her. It reflects the underlying tension and concern for her wellbeing, contrasting with any excitement or normalcy experienced by those around her, thus highlighting her personal struggles.
The other options, while they may contribute to the overall narrative, do not as effectively encapsulate the weight of Clara's challenges as the doctor's worried expression does.