谁能帮我解释一下GWD14的此题，不懂的说

Q21:

That twenty-one ceramic dog figurines were discovered during the excavating of a 1,000-year-old Hohokam village in Tempe, Arizona, has nearly doubled the number of these artifacts known to exist.

1. That twenty-one ceramic dog figurines were discovered during the excavating
2. Twenty-one ceramic dog figurines discovered at the excavation
3. Discovering twenty-one ceramic dog figurines at the excavating
4. Ceramic dog figurines, twenty-one of which were discovered during excavating

E      The discovery of twenty-one ceramic dog figurines during the excavation

这题为什么选E呢，我觉得B好象也有道理的。

谓语动词为单数HAS，所以主语应该为the discovery