Ultrasonography of right subclavian vein

Which of these statements regarding radiographic contrast is false?

A) There are few shades of gray in a radiograph with short-scale contrast. B) Short-scale contrast describes a radiograph in which the density differences between adjacent areas are large. C) There are many shades of gray in a radiograph with long-scale contrast. D) Long-scale contrast describes a radiograph in which the density differences between adjacent areas are large.

Which of the following identifies the cause and corrective action for an image with overlapping of the proximal contacts in which the overlap appears more severe in the posterior region than the anterior region?

A) Mesiodistal projection of the central ray caused the error. Shift the tube toward the anterior to correct this error. B) Mesiodistal projection of the central ray caused the error. Shift the tube toward the posterior to correct this error. C) Distomesial projection of the central ray caused the error. Shift the tube toward the anterior to correct this error. D) Distomesial projection of the central ray caused the error. Shift the tube toward the posterior to correct this error.