Please answer my question!

1. Newton thought that there must be a power connecting objects, the idea that is proved true.
2. Newton thought that there must be a power connecting objects, which is the idea that is proved true.

Q1) Do these two sentences sound natural and are they grammatically correct?

I think they sound natural and grammatically correct.

Q2) Could you tell me what "the idea" and "which" refers to in each sentence?
A: Newton thought that there must be a power connecting objects
B: that there must be a power connecting objects

I think the correct option is B.

Please check whether my thinking is correct.