[求助]请教GWD02 33

1. When an active tooth in the shark’s jaws is lost or worn down, many spare teeth lie in seemingly limitless reserve, each of which are ready to slide into the appropriate position.
2. Whenever an active tooth is lost or worn down, many spare teeth lie in seemingly limitless reserve in the shark’s jaws, which are each ready to slide into the appropriate position.
3. Many spare teeth lie in seemingly limitless reserve in the shark’s jaws, each one of which are ready to slide into the appropriate position when an active tooth is lost or worn down.
4. The many spare teeth lying in seemingly limitless reserve in the shark’s jaws, each one of which is ready to slide into the appropriate position whenever an active tooth is lost or worn down.
5. In the shark’s jaws, many spare teeth lie in seemingly limitless reserve, each one ready to slide into the appropriate position whenever an active tooth is lost or worn down.

when引导的状语不是只是修饰后半句吗？牙掉了，后面的牙补上来。但是牙齿是一直都无限的。选E不是更好？

那应该用什么呢？用each?还有那个whenever 和when 有没有区别阿？