Option A. This option in the first clause does not create a counterbalance that would be repelled by the second clause, so, therefore, it does not fully give a perfect type of answer.
Option B.
This is the correct answer.this option created a first clause that needs to be counterbalanced in the second clause. That is, the first clause is a fact that stand and the second starting with ' but' gives a reason why it should not be.
Option C.
'would seem' here is incorrect.Its usage contradicts the sentence. Thus, this option is correct.
Option D.
'Now living...' this is not a perfect intro to the sentence, also the use of although as a 'separater' here is improper, 'but' would have been better.
Option E.
'since' the use of 'since' does not make the sentence contrast each other therefore this option is wrong