符合十二指肠球后溃疡的临床特征的是（）

A.多发生在十二指肠球部后壁

B.易导致幽门梗阻

C.易并发出血

D.易发生癌变

E.临床症状多不明显

An analyst does research about efficient frontier. Which statement is the least likely the character of the efficient frontier（）

A. Minimize risk for a given return target.

B. Slope decrease along the curve.

C. Have the same utility for investors.