Experts believe
the sheer variety of cars in all segments makes it difficult for buyers to choose one model over the other, and this is where marketing makes a difference.
(A) the sheer variety of cars in all segments makes it difficult for buyers to choose one model over the other Incorrect as the sentence misses that after believe meaning that experts believe the sheer variety of cars not the whole clause after believe
(B) that the sheer variety of cars in all segments makes it difficult for buyers to choose one model over another Correct
(C) that the sheer variety of cars in all segments makes difficulty for buyers to choose one model over another Incorrect due to wrong usage of difficulty.
(D) that the sheer variety of cars makes it difficult for buyers in all segments to choose among models Incorrect due to wrong placement of in all segments
(E) the sheer variety of cars in all segments makes it difficult for buyers in choosing one model over another Incorrect as the sentence misses that after believe meaning that experts believe the sheer variety of cars not the whole clause after believe