What i think you did a typo
The correct answer is B because a semi-colon is the best way to join the two sentences since they are both independent.
Hope this helps :)
The square root of 4225 is 65. You can check this by multiplying 65 x 65.
The excerpts from the passage which provide strong evidence that Hrothgar’s hall is famous throughout the lands are: B and C.
B) Nobody on earth knew of another building like it. This excerpt reflects how this place was unique, therefore very famous among all the people. Nobody could even imagine a building like this because everybody knows this exact place.
C) Majesty lodged there, its light shone over many lands. The descriptive elements of these lines point out that this place is known by anyone from any land, as if it can be seen from elsewhere. 'its light shone over many lands' and people from many lands know its light.