The answer is A.
EXPLANATION: The lead strips in a focused grid are made to parallel the x-ray beam. Therefore, scattered radiation, which radiates in directions other than that of the primary beam, will be absorbed by the grid. When the x-ray beam does not parallel the lead strips, some type of grid cutoff occurs. If the x-ray beam is not centered to the grid, or if the x-ray tube and grid surface are not parallel (level), there will be a fairly uniform decrease in radiographic density across the entire image. However, if the grid is not used within its recommended SID (focus) range (ie, if the SID is too great or too little), there will be a decrease in density at the periphery of the image