为何c不对

问题如下：

The following are the characteristics of preferred stock, except:

选项：

A.

Prefferred stocks are either callable or putable.

B.

Prefferred stocks generally do not have voting rights.

C.

Prefferred stocks do not share the company's business performance.

解释：

A is correct.

Preferred stocks do not have to be either callable or putable.

考点：Characteristics Of Equity Securities

A选项错在它说的是优先股必须是附带权利的（不是callable就是putable），其实绝大多数优先股是不附带权利即普通的优先股，只有少数是附带权利的。因此A说的太绝对了。所以答案说Preferred stocks do not have to be either callable or putable.即优先股不一定非要是callable或putable。