Sentence Correction

Visby is the largest city on the Swedish island of Gotland; arguably the best-preserved medieval town in Scandinavia, and has become a World Heritage Site.

(A) arguably the best-preserved medieval town in Scandinavia, and has become a World Heritage Site.
(B) it is arguably the best-preserved medieval town in Scandinavia, and, as a result of this, has become a World Heritage Site.
(C) arguably the best-preserved medieval town in Scandinavia, it has become a World Heritage Site.
(D) it has become a World Heritage Site, and arguably the best-preserved medieval town in Scandinavia.
(E) is arguably the best-preserved medieval town in Scandinavia, a World Heritage Site.

The OA is D.

I wonder why D is chosen over B. Is it simply because of "conciseness"? I find that D is not grammatically correct. Because "......and arguably the best-preserved medieval town in Scandinavia." is neither constructed parallelly nor has got any verb.

Please share your thoughts.

I was also puzzled between B and D. But , B has a meaning change because it is preserved it has become a world heritage site.

And D says its a world heritage site besides the best preserved ........

Schawjibb wrote:Visby is the largest city on the Swedish island of Gotland; arguably the best-preserved medieval town in Scandinavia, and has become a World Heritage Site.

(A) arguably the best-preserved medieval town in Scandinavia, and has become a World Heritage Site.
(B) it is arguably the best-preserved medieval town in Scandinavia, and, as a result of this, has become a World Heritage Site.
(C) arguably the best-preserved medieval town in Scandinavia, it has become a World Heritage Site.
(D) it has become a World Heritage Site, and arguably the best-preserved medieval town in Scandinavia.
(E) is arguably the best-preserved medieval town in Scandinavia, a World Heritage Site.

The OA is D.

IMO A/D - are fragments (part before AND in A and part after AND in D are fragments)
B - best choice but does not carry the intended meaning
E - lack main subject; what does "a World Heritage Site" modify - Scandinavia!
C - "arguably the best-preserved medieval town in Scandinavia" modifier of IT - we may say IT can refer to Scandinavia (IMO that may not be right interpretation as remmoving the modifier IT can refer to Visby; moreover IT and Visby play the same role of main subject in their respective clauses)

[spoiler]IMO C (diagree with D)[/spoiler]

Eliminate A, C and E. The sentences separated by commas should be able to stand alone(main subject and main verb).
B) states that it has become a world heritage site because it is arguably the best preserved site. But the original sentence they are in parallel and not a causal affect of each other.
D) After elimination only D remains.