Consider the following simplified digital image, which has a 3 x 3 grid with four gray levels numbered from 0 to 3. It shows the number 1 in dark gray on a light gray background. Let A be the 3 x 3 matrix that represents this image digitally.Find a matrix B such that subtracting B from A will cause the entire image to become lighter by one gray level. Evaluate the expression A - B.