GWD13-7没有讨论过

Which of the following most logically completes the argument?

A significant number of Qualitex Corporation’s department heads are due to retire this year.  The number of employees other than current department heads who could take on the position of department head is equal to only about half of the expected vacancies.  Oualitex is not going to hire department heads from outside the company or have current department heads take over more than one department, so some departments will be without department heads next year unless Qualitex ______.

1. promotes some current department heads to higher-level managerial positions
2. raises the salary for department heads
3. reduces the number of new employees it hires next year
4. reduces the average number of employees per department
5. reduces the number of its departments

这道题为什么选Ｅ啊，划线部分什么意思啊

这题目应该不难啊，关键是题目没看懂吧？划线部分意思基本是：除目前这些部门头头以外，可以担任部门头头的公司员工数量只有将出现的空缺职位数量的一半。

整题大概意思是，那公司部门头头今年有很多要退休，因此有很多头头的位子要空出来。但是除目前这些部门头头以外，可以担任部门头头的公司员工数量只有将出现的空缺职位数量的一半。这公司不会从外面雇佣人来当头，也不会让现有的头头再兼任另外部门的头，也就是不会有足够的人来担任所有的头头的位子，那么明年这公司的一些部门就会没有头头，除非（下面就是结论了）除非就是关闭一些部门。这个逻辑应该很清楚的。

为什么A不对呢？