A Radiograph of an AP Projection of the Lumbar Spine

A radiograph of an AP projection of the lumbar spine on an average-size patient reveals that the psoas major muscles and transverse processes are not visible.The following analog factors were used for this projection: automatic exposure control (AEC) with center ionization chamber, 95 kV, 40-inch (102-cm) SID, grid, and 14- × 17-inch (35- × 43-cm) image receptor.Which of the following modifications will be most effective in demonstrating these structures?

A) Decrease the kV.
B) Activate all three ionization chambers.
C) Decrease the mAs.
D) Increase the kV.