What is the primary purpose of filters in x-ray machines?

The primary purpose of filters in x-ray machines is to absorb harmful long wavelengths, which aligns with option C. In radiography, filters are essential for enhancing patient safety by reducing the patient's exposure to low-energy x-rays, which contribute little to diagnostic image quality but increase radiation dose.

These low-energy x-rays are less penetrative and are more likely to be absorbed by the body's tissues rather than passing through to the image receptor. By utilizing filters, such as aluminum or copper, the x-ray machine can eliminate these less useful wavelengths, allowing for a more optimal beam that not only improves the overall quality of the imaging but also minimizes unnecessary radiation exposure to the patient.

This process of filtration is crucial in ensuring that only the high-energy, penetrating x-rays are emitted, providing a more effective diagnostic image and safeguarding the health of the patient against unnecessary radiation.