时态问题：完成时和ago能不能搭配？

billkp

OG13第十题：
The widely accepted big bang theory holds that the universe began in an explosive instant ten to twenty billion years ago and has been expanding ever since.

E:the universe to have begun in an explosive instant ten to twenty billion years ago and has been expanding

原句是对的。答案E，OG上说因为不平行所以错。那么是不是只要改成平行E就对了呢？
the universe has begun in an explosive instant ten to twenty billion years ago 的表述可以么？

还有，ten to twenty billion years ago   是修饰instant的还是修饰begun这个动作的？