require 虚拟语气的should一定要省略吗？

找不到我

The CEO has proposed a new policy requiring that employees should retain all pensions indefinitely or be allowed to cash them in at retirement.

• A that employees should retain all pensions
  
• B that all pensions be retained by employees
  
• C the retaining by employees of all pensions
  
• D employee's retention of all pensions
  
• E employees to retain all pensions
  
  

这题选择E选项，但我觉得虚拟语气和require sb to do 都对呀，A错是因为虚拟语气中的should一定得省略吗