Noise can be reduced by performing which of the following actions?

Noise in imaging can significantly affect the quality of a diagnostic image, and various techniques can be employed to minimize it. Increasing collimation is particularly effective in reducing noise because it specifically limits the area of the radiated beam to just the region of interest. By reducing the amount of scatter radiation that reaches the image receptor, collimation can enhance the contrast and clarity of the image, which in turn makes any underlying noise less noticeable.

While using a grid can help reduce scatter and improve image quality, and decreasing technique may lower exposure but can also lead to increased noise if the technique is pushed too low. The option selected as the answer focuses solely on the technique of collimation, which is universally recognized as a direct method to reduce noise by controlling the amount of unwanted radiation that contributes to the overall image composition. This approach enhances the signal-to-noise ratio, resulting in clearer images.