Suppose That the Maximum Depth of Visualization Using a 3

Multiple Choice

Suppose that the maximum depth of visualization using a 3.5-MHz transducer is 14.2 cm. On the previous two tests, 3 months and 6 months earlier, it was 14.4 and 14.1 cm, respectively. These variations should be interpreted as

A) just barely tolerable performance.
B) normal variations inherent in the machine.
C) excessive variations, indicating that the machine requires immediate service.
D) normal variations inherent in the measurement process.