Which sentence is the correctly written compound sentence?

AThe Statue of Liberty is located on a small, uninhabited island called Liberty Island.
BLiberty Island is a small, uninhabited island where the Statue of Liberty is located.
CLiberty Island is a small, uninhabited island, it is best known as the location of the Statue of Liberty.
DLiberty Island is a small, uninhabited island, but it is best known as the location of the Statue of Liberty.

Verified Answer :

The correct compound sentence is C. Liberty Island is a small, uninhabited island, it is best known as the location of the Statue of Liberty.

Since a compound sentence consists of at least two independent clauses usually connected with a conjunction, the correct answer is D. Because there are two independent clauses: 1. Liberty Island is a small, uninhabited island, + but + 2. it is best known as the location of the Statue of Liberty. It is the only correctly written compound sentence, because of BUT.