A general rule often employed for determining the kilovoltage to be used when X-raying a part is that:

The kilovoltage should be as high as other factors will permit.

The kilovoltage should be as low as other factors will permit.

The kilovoltage is always a fixed value and cannot be changed.

The kilovoltage is not an important variable and can be changed over a wide range without affecting the radiograph.

None of the above.