Which action minimizes the appearance of grid lines on a radiographic image?

Using a moving grid effectively minimizes the appearance of grid lines on a radiographic image because the movement of the grid during the exposure allows for the blurring of lines that would typically appear in a stationary grid. This motion distributes the exposure over a wider area, which mitigates the sharpness of the grid lines on the final image. As a result, the grid lines become less noticeable, leading to a cleaner image.

In contrast, decreasing grid frequency or increasing grid ratio would not address the issue of visible lines but rather alter the overall image contrast and exposure. Angling across the grid is not a standard practice to eliminate grid lines and could potentially create other imaging artifacts. Hence, employing a moving grid is considered the most effective method to reduce grid line visibility in radiographic images.