On the Viewing Monitor of a Scanner, a Sonographer Counts

On the viewing monitor of a scanner, a sonographer counts 16 shades of gray in the gray-bar pattern. The hard-copy B-mode image displays only the 13 brightest gray bars. This should be interpreted as

A) normal performance.
B) too low a receiver gain.
C) inadequate photography and processing that need correction.
D) poor contrast and brightness settings on the viewing monitor.