Final answer:
The percentage of the total energy applied to an x-ray tube target that is converted into x-rays is around 1% to 10%.
Step-by-step explanation:
The percentage of the total energy applied to an x-ray tube target that is converted into x-rays can vary depending on the efficiency of the x-ray tube. In general, a small fraction of the energy is converted into x-rays, while the rest is dissipated as heat. For most x-ray tubes, the percentage of energy converted into x-rays is around 1% to 10%.
If we consider the given options, the most appropriate choice would be 1%, as it represents the lower end of the typical range of energy conversion.