Of the following signs and symptoms of bowel obstruction, which is related primarily to small bowel obstruction rather than large bowel obstruction

A. Profuse vomiting.
B. Cramping abdominal pain.
C. Abdominal distention.
D. High-pitched bowel sounds above the obstruction.

凯恩斯认为人们的需求动机有：货币的（）动机。

A.交易

B.预防

C.投资

D.投机