Correct Option: D
Although he is most famous for creating exquisite jewelry,
Louis Comfort Tiffany was also an important innovator in the fields of architecture and interior design during the Art Nouveau movement of the early 20th century.
We need a Modifier to modify "Noun modifier" (he is most famous for creating exquisite jewelry - modify Louis Comfort Tiffany), not a conjuction
A. Being that -
"Being" goes only with Human or Alien such as "Human being" or "Alien Being", never to be address to pronoun, Noun, phrase, clause or modifier
B. Because - usage max when it is with cause and effect related statement, "becasue" is used as conjuction, not as a modifier
C. Whenever - usage while addressing "TIME specific", it can be used as conjuction and interrogative adverb kind statement
D. Although - can be used as a Modifing Noun, but without a conjuction verb, here it modifies Noun as mnetioned above
E. Not with standing the fact that - wrong phrase to modify Noun Modifier, we need Prepositional Phrase