Which of the Following Statements About Abdominal and Retroperitoneal Sonography

Which of the following statements about abdominal and retroperitoneal sonography is untrue?

A) Evaluation of the abdominal arteries for the presence of an aneurysm is a clinical indication for abdominal sonography.
B) Abdominal sonography should be done after other diagnostic imaging tests that require contrast material.
C) Obesity and dehydration may make it more difficult to obtain satisfactory images of the abdominal organs.
D) Patients should refrain from smoking or chewing gum, because this can introduce air into the stomach.