Sometimes conjunctions combine two sentences, which are are not related and the second sentence contains an opposing idea which the reader does not expect. Such conjunctions are called concessional conjunctions. Examples are: Nevertheless, nonetheless, despite, even though, although, etc. 

In the given example: A person who is a great poet is not normally expected to be an exceptionally talented singer as well. However, Tansen was one. Hence, we have to use a concessional conjunction. Option B is correct because "nevertheless" is a concessional conjunction. 

Option A:  “As a result” is often used as a conjunction to indicate cause-and-effect relationships. It is used when one sentence is the cause of another. Here, one sentence is not the cause of the other. Hence, this conjunction cannot be used. This option is incorrect.

Option C: "Likewise" is used, when the two sentences being joined are similar.  However, the two given sentences communicate two different ideas which normally don't appear together. Hence, this option is incorrect.

Option D: "So that " is a conjunction used to indicate cause-and-effect relationships. Here, one sentence is not the cause of the other. Hence, this conjunction cannot be used. This option is incorrect.